New xenophytes from La Palma ( Canary Islands , Spain ) , with emphasis on naturalized and ( potentially ) invasive species – Part 3

New xeNophytes from La paLma (CaNary IsLaNds, spaIN), wIth emphasIs oN NaturaLIzed aNd (poteNtIaLLy) INvasIve speCIes. part 3.— Several months of field work in La Palma (western Canary Islands) yielded a number of interesting new records of non-native vascular plants. Alstroemeria aurea, A. ligtu, Anacyclus radiatus subsp. radiatus, Chenopodium album subsp. borbasii, Cotyledon orbiculata, Cucurbita ficifolia, Cynodon nlemfuensis, Datura stramonium subsp. tatula, Digitaria ciliaris var. rhachiseta, D. ischaemum, Diplotaxis tenuifolia, Egeria densa, Eugenia uniflora, Galinsoga quadriradiata, Glebionis segetum, Kalanchoe laetivirens, Lemna minuta, Ligustrum lucidum, Lotus broussonetii, Oenothera fallax, Paspalum notatum, Passiflora caerulea, P. manicata × tarminiana, P. tarminiana, Pelargonium capitatum, Phaseolus lunatus, Portulaca trituberculata, Pyracantha angustifolia, Sedum mexicanum, Trifolium lappaceum, Urochloa mutica, U. subquadripara and Volutaria tubuliflora are naturalized or (potentially) invasive xenophytes or of special floristic interest, reported for the first time from either the Canary Islands or La Palma. Three additional, presumably ephemeral taxa are reported for the first time from the Canary Islands, whereas seven ephemeral taxa are new for La Palma.


INTRODUCTION
This paper is a sequel to Verloove (2016 and. We present new records for species that are either new to the Canary Islands (and even Macaronesia as a whole) or new to the island of La Palma. The emphasis is on species that are naturalized or on their way to future naturalization, (potentially) invasive or that are otherwise of interest. Records of (mostly) occasional garden escapes or (presumably) ephemeral introductions ("casual alien plants" sensu Richardson et al., 2000) are only briefly commented.

MATERIALS AND METHODS
Records here presented are the result of several months of fieldwork in La Palma conducted by the first author, mainly between 2014 and 2018. In addition, specimens collected by the first author during the last decades have been re-examined. Voucher specimens of most taxa are preserved in the private herbarium of the first author (hereafter as "pers. herb. RO"). Duplicates were often deposited in the herbarium of the Botanic Garden Meise, Belgium (BR) (acronym according to Thiers, 2019).
The actual presence or absence on the island of La Palma of the non-native taxa here presented was each time compared with data provided by Hohenester & Welss (1993), Acebes Ginovés et al. (2010), the Euro+Med PlantBase (Euro+Med, 2006 and the Banco de Datos de Biodiversidad de Canarias (2019). For some recently introduced species several additional papers were checked as well.
The paper is divided in three parts. The first and major part deals with either probably and/or locally naturalized or (potentially) invasive species or species that are otherwise of particular interest. Each entry includes the scientific name of the taxon (if useful accompanied by one or more homo-or heterotypic synonyms), the family to which the taxon belongs (see below), kind of chorological novelty, enumeration of selected herbarium collections and/ or personal observations (often also with exact locality indication, using Google Maps coordinates, given in decimal degrees), origin (primary as well as secondary distribution range), known distribution in the Canary Islands (abbreviated as follows: H = El Hierro, P = La Palma, G = La Gomera, T = Tenerife, C = Gran Canaria, F = Fuerteventura, L = Lanzarote) and its estimated degree of naturalization in La Palma (sensu Richardson et al., 2000). If relevant, some additional information is also provided (nomenclatural or taxonomic comments, identification keys, etc.). In the second and third part records of (presumably) ephemeral aliens are presented. These may be either new to the Canary Islands or new to the island of La Palma. For these records only herbarium data and personal observations are referred to. For convenience, within each of these parts, all taxa are presented in alphabetical order.
Familial and generic classifications are in accordance with APG IV (2016). For the taxa treated herein this means, for instance, that Chenopodiaceae are included in Amaranthaceae and Lemnaceae in Araceae. Assessing the exact residence status in the Canary Islands in general, or the island of La Palma in particular for each individual species, is not straightforward. All taxa except those that are quoted as surely native for La Palma ("nativa seguro") by Acebes Ginovés et al. (2010) were considered non-native in this paper.
Origin: native to southern South America (Chile, Argentina), cultivated worldwide in countless cultivars and hybrid forms.
Known distribution in the Canary Islands: C .
Alstroemeria ligtu is here accepted in a broad sense. The true A. ligtu (incl. several subspecies) is barely cultivated on La Palma. However, there are an immense number of garden forms and intra-and interspecific hybrids that are commonly grouped under 'Ligtu hybrids' or Alstroemeria ×hybrida hort. These cultigens show a broad variation in all features, especially regarding the color and pattern of the perigone and are often ornamental elements of house gardens. Loisel., Fl. Gall. 2: 583 (1807) subsp. radiatus (Asteraceae). New to the flora of La Palma. Spain,La Palma: Puntallana,, fallow land on the edge of the road, 04.IV.2017, R. Otto 22558 (pers. herb. RO, dupl. BR); Breña Alta, San Isidro, near the crossing of LP-301 and Canal de Fuencaliente, fallow land, 05.IV.2017, R. Otto (pers. obs.).

Anacyclus radiatus
Origin: native to the western Mediterranean region, North Africa and the Canary Islands, known as casual alien from Madeira, naturalized in the Azores.
Degree of naturalization: naturalized. Origin: native to Italy and Romania (Euro+Med, 2006. Little is known about its exact origin, but it can be assumed that it comes from the southern parts of Europe or the Mediterranean region. It is introduced as a rare casual in the western and northern parts of Europe, but "usually not flowering and never setting seed in Norden" (Uotila, 2001).
Degree of naturalization: naturalized.
This subspecies seems to be not rare on La Palma. It was also seen in disturbed places in or near Breña Baja, El Paso, Los Llanos, San Andrés y Sauces and Sta. Cruz de La Palma, mostly between 200 and 700 m, sometimes together with Ch. album subsp. album and Ch. probstii Aellen, both with similar ecological requirements. It was surely overlooked on La Palma in the past or confused with the similar type subspecies, and this may be true for the other islands as well.
Both subspecies are distinguished in the following couplet, modified from Wißkirchen & Walter (2014). The lower and middle leaves on the main stem are important for the determination.
Origin: Cotyledon orbiculata is native to southern Africa and introduced worldwide in warm climates as a garden ornamental plant, naturalized in southern Australia, California, New Zealand (Weber, 2017) and Italy (Gallo, 2017); present in France, India (CABI, 2019) and Spain (CABI, 2019;sub C. macrantha).
Known distribution in the Canary Islands: C .
Cotyledon orbiculata is an extraordinarily variable species, divided into five varieties and a great number of poorly distinguishable cultivars (Jaarsveld, 2003). According to Tölken (1979) our plant is similar to both var. spuria and var. oblonga. For Tenerife the occurrence of Cotyledon macrantha is indicated (Acebes Ginovés et al., 2010). This is an unresolved name but probably belongs in the synonymy of C. orbiculata L. var. orbiculata (Jaarsveld, 2003).
According to Weber (2017) C. orbiculata is invasive in southern Australia and New Zealand, mostly in coastal scrub and rock outcrops.
The frequency with which this species is used in gardens is astonishing in view of the strong toxicity of all plant parts, especially for goats and sheep, but also for dogs, horses, cattle and poultry (Fuller & McClintock, 1986). The contained "cotyledon toxin" is a highly potent neurotoxin and people who   Origin: native in the highlands of Central America and Mexico, cultivated in North and South America, Europe and Asia.
Degree of naturalization: ephemeral, but some occurrences persistent for several years.
The fig-leaf gourd is a perennial, very vigorous and widely creeping or climbing plant. In contrast to its one-year cultivated relatives C. maxima (Duchesne) Duchesne ex Poir., C. moschata Duchesne and C. pepo L. the plant is more cold tolerant and shows a higher resistance to various diseases (e.g. fusariosis of cucumbers) and is therefore (e.g. in Central Europe) used as a grafting stock for cucumbers. On La Palma, the plant is quite often cultivated in house gardens, probably especially for the production of desserts (cabello de ángel, dulce de calabaza), even the roasted seeds are eaten. For more information about the use and culture of this exceptional pumpkin see e.g. http://www.joseanalija.com/la-calabaza-cabello-de-angel/. The occurrences in the wild are the result of distribution by seeds (for example from bird seed mixtures) or by outgrowing of cultivated specimens into the nearer environment. At suitable locations plants can outlast for a few years. It is probably overlooked or misunderstood.
The separation of the four mentioned Cucurbita species is most secure on the basis of fruiting plants. It can be done according to the key below (modified from Hamer & Hanelt, 2008;Scholz, 2008;Nesom, 2015). It should be noted that also interspecific hybrids are in culture as vegetables (e.g. C. moschata × C. pepo) or for use as the preferred rootstock (C. maxima × C. moschata) for watermelons, melons and cucumber (Karaağaça & Balkayab, 2013).

1.
Seeds black, brown-black or dirty white (very rarely white); leaves similar to fig leaf, roundish to kidney-shaped, 5-lobed with rounded sinuses between the lobes, basis heart-shaped and their basal edge ± serrate, ± hirsute, blade often mottled with silvery green; stems angular and mostly sparsely stiff-haired, without markedly papillose based hairs, creeping to 25 m and more; fruit ± round or obovate, up to 30 cm long, green, mostly with longitudinal white lines or stripes distally, irregularly linearly spotted; fruit stem rounded 5-ribbed and not or only  conspicuous cross-walls and much shorter and finer hairs, without pustulate based hairs; stems lying down, ± roundish, not sharp-edged; leaves of mostly soft consistency, often marbled in green-white, plant without markedly papillose based hairs, leaf-blade 5 or 6 lobed, fruit mostly oblate or somewhat clavate, pruinose; calyx lobes often widened on their tips or even foliaceous .. New to the flora of the Canary Islands. Spain, La Palma: Villa de Mazo, Belmaco, next to Archeological Park Belmaco; from the parking lot on approx. 70 m length along the right side of the LP-2 in the direction of Sta. Cruz a large occurrence at the roadside, at the unpaved parking strip, at the road embankment and partly reaching far down into the terraced slope (formerly cultivated land); the strong lawn grows on the open and sun-exposed areas between higher bushes almost in pure stands, spreads over the asphalt and overgrows walls and lower bushes; perhaps intentionally or unintentionally applied for attachment of the embankment, 360 m, ca. 28.578338º N, 17.776081º W, 13.X.2017, R. Otto 23031 (pers. herb. RO, dupl. BR); ibid., much more flowering culms, striking fresh-green color of the juicy lawn, 01.IV.2018, R. Otto 23115 (pers. herb. RO, dupl. BR).
Origin: native to Africa, introduced as good pasture grass and for the production of valuable hay (Wouw et al., 2009) as well as for soil stabilization in many parts of the tropics and subtropics worldwide and naturalized.
Degree of naturalization: locally naturalized and potentially invasive.
The grass is reported as invasive for instance from the Hawaiian Islands (US Forest Service, 2019), from Costa Rica, Cuba, Mexico and Puerto Rico (CABI, 2019). In Galápagos it has only been observed in a couple of places, but it is feared that it may in future become the most severely invasive of all grass species (Laegaard & Pozo García, 2004 Fig. 10), the stems are up to 60 cm (and more) high and 1-2(3) mm thick at the bottom. Each inflorescence consists of usually only a single whorl of 3-13 spikes, that are 4-11 cm long. The propagation of the species is possible by seed but is mainly vegetative by its creeping stolons or by parts of their above-ground stems because the plants are rarely flowering, and their seed set is low (CABI, 2019). So, it is possible that sterile Cynodon turfs in the Canaries also belong to C. nlemfuensis.
This species is able to overgrow large areas in a short time. A plant excavated in La Palma at the beginning of April 2018 developed stolons of over 4 m in length in pot culture in the garden of the first author in Germany until the beginning of August 2018 (under probably not optimal conditions)! The very competitive species has obviously transformer qualities. The strong, many meters long and highly branched stolons lie on the ground and on top of each other as ± dense "multi-storey", sometimes nearly knee-high mats. The stolons cover shrubs such as Kleinia neriifolia Haw., Rumex lunaria L. or Opuntia sp. and eventually lead to a very species-poor plant community, e.g. with the climbing Bryonia verrucosa Dryand. as a stubborn and striking companion plant.

1.
Racemes 3-9, slender and often somewhat flexuous, (2)4-7(10) cm long; lemma hairy on keel; leaf blades 2-5 mm wide, sometimes with scattered hairs; stout stolons and rather slender culms of 1-1.5 mm diameter, forms loose mats up to 40 ( -. Racemes 5-13, spreading, often rather flexuous, 6-11 cm long; lemma sparsely hairy on keel; leaf blades 5-6 mm wide, glabrous or nearly so; coarse plant with culms about 90 cm tall and 2-5 mm Most likely our plant belongs to var. nlemfuensis, but the characteristics overlap and hybrids and several cultivars exist. One of them, ʻOkeechobeeʼ for instance, is known as a contaminant in the stands of C. dactylon cv. ʻCallieʼ (Cook et al., 2005), so a contamination of lawn seed (e.g. for soil stabilisation) could also explain the occurrence of the grass in La Palma.
The taxonomic value of these varieties is questionable. Stolons of the La Palma plants were cultivated in Germany (April-September 2018). The obtained plants look significantly different: leaf laminas are practically hairless (vs. ± numerous hairs on tiny nodules), are up to 5-7(8) mm wide (vs. 2-5 mm) and culms are 2-2.5 mm wide at base (vs. 1-1.5 mm). The plants developed numerous strong stolons 3-3.5 mm wide and up to 4 m long in four months. Unfortunately, no racemes were developed. One could say that, under cultivation ex situ, some characteristics shifted towards var. robustus.
This extraordinary variety of the highly polymorphic and widespread weedy Digitaria ciliaris seems to be restricted so far to South America (Vega & Rúgolo de Agrasar, 2003).
It is characterized by the presence of scattered, papillose based, long glassy hairs on the raceme rachis and/or pedicels. On the specimens of La Palma, these hairs were (3)4-7(8) mm long and concentrated on the lower third of the racemes and varying in numbers.
In his monograph Henrard (1950) characterizes this taxon as follows: "It has combined characters Figure 11. Herbarium specimen of Digitaria ciliaris var. rhachiseta with scattered, papillose based, long glassy hairs on the raceme rachis, Nr. 23000 pers. herb. RO, Breña Alta, coll. 08.X.2017 (photographs: R. Otto). of two different species, belonging to different sections, viz: D. adscendens and D. horizontalis." and he sums up after the description of the individual characteristics: "Hitherto only known from Colombia, a region from which both species are known. The plant may represent a crossing between the two species." This variety is reported here because there is a risk of confusion with two other similar, weedy representatives of D. subg. Digitaria sect. Digitaria, wich also can bear such papillose based long hairs on their raceme rachis, namely Digitaria nuda Schumach. (p.p.) and D. horizontalis Willd. These three taxa can be distinguished as follows (modified from Pohl, 1980;Nozawa et al., 2017).  Origin: southern Europe and western Asia, naturalized in many temperate regions worldwide.
Degree of naturalization: ephemeral but possibly invasive.
The species is reported as invasive from the southwestern region of the United States (White, 2013), from California (EDDMapS, 2019), and from Argentina (Busso et al., 2013).
The observations of Diplotaxis tenuifolia in the Canary Islands have been increasing in recent years (see above). This is due (as in mainland Europe or North America) to increased commercial and private cultivation (sale of potted plants and seeds) in recent decades. This perennial Diplotaxis species is used as a salad and spice plant (product name often "Italian arucula") and increasingly replaces the annual Eruca sativa L. ("arucula") due to the higher drought-resistance and its easier cultivation. Origin: South America, commonly cultivated as aquarium plant worldwide and naturalized as an aquatic weed in stagnant or slow-flowing water in temperate to tropical regions.
Egeria densa is reported as invasive from Australia, Central America, Mexico, New Zealand and the United States (US Forest Service, 2019).
The above occurrence may also refer to a deliberate introduction (since in the neighboring basin also several specimens of Pistia stratiotes L. were observed) but should be mentioned here for several reasons.
According to information from local residents, the species forms mass populations in water tanks etc., which unfortunately could not be verified because of difficulties of access to such facilities. Egeria densa could be more widespread in any case and it should therefore be paid special attention to this taxon on the islands. There is a high risk of confusion with similar Hydrocharitaceae species, especially with Hydrilla verticillata (L.) Royle. The first author has seen several mass occurrences of this species in water tanks in the vicinity of Sta. Cruz de La Palma (Otto & Verloove, 2016). The most important differences of some easy-toconfuse species are presented in the following key (modified from Weyer & Schmidt, 2010;Nelson, 2011;and Scannell, 2011). Origin: South America, cultivated in many cultivars for its edible fruits and naturalized in many tropical and subtropical regions worldwide.
Degree of naturalization: ephemeral but possibly invasive.
Eugenia uniflora is reported as invasive from Australia, Cook Islands, French Polynesia, Hawaiian Islands, Mauritius, La Réunion (US Forest Service, 2019) and is probably a hitherto overlooked element of the Canary Islands xenophyte flora. It is possibly dispersed by birds. Ruiz & Pav., (1798)  Origin: native to Central Mexico, now a cosmopolitan weed of disturbed areas in temperate and subtropical regions.

Galinsoga quadriradiata
Known distribution in the Canary Islands: G, T (Acebes Ginovés et al., 2010) C . Galingsoga quadriradiata was first reported from La Palma by Brandes (2005). However, this information was not included in the list of Acebes Ginovés et al. (2010).
Degree of naturalization: naturalized and invasive.
Seen very frequently throughout the island in gardens, cultures of vegetables and by roadsides, sometimes in abundance, at times together with  Known distribution in the Canary Islands: G, T, C (Acebes Ginovés et al., 2010).
Degree of naturalization: naturalized.  Kalanchoe laetivirens, a species close to K. daigremontiana Raym.-Hamet & H. Perrier, has rarely been seen on La Palma in culture so far. Like other Kalanchoe species with the ability to produce plantlets at the edges of leaves, e.g. K. daigremontiana, K. delagoensis Eckl. & Zeyh. and K. ×houghtonii, K. laetivirens also has the ability to develop into a weed (or an invasive species) in a near future. Origin: temperate to tropical America, introduced as an aquatic weed and now established in many parts of Europe (see DAISIE, 2019).
Degree of naturalization: probably in the process of naturalization.
Lemna minuta could have been present on La Palma for quite some time, but it is certainly not a very common species. It was first observed on La Palma by the first author in October 2013 [Villa de Mazo, water basin in a foil greenhouse, together with Eichhornia crassipes (Mart.) Solms, Salvinia molesta D. S. Mitchell and Azolla filiculoides Lam.]. Since then the species was searched for but with limited success. This is somewhat surprising in view of its rapid spread on the European continent. Since many of its potential habitats on La Palma (mainly water tanks) are inaccessible, it may be more widespread.
However, the duckweed flora on La Palma is clearly dominated by the highly invasive species Landoltia punctata (Otto & Verloove, 2016). The first author is not aware of any current occurrence of Lemna gibba L. and only a few occurrences of Lemna minor L. Perhaps the delicate and thin L. minuta (and also L. minor) is less competitive under the Canarian environmental conditions against the robust and thermophilous Landoltia punctata.
This semi-evergreen large ornamental shrub or small tree is reported as invasive for instance from Argentina (Busso et al., 2013), from Australia, Florida and New Zealand (US Forest Service, 2019) an it is on the list of "Hawaii's most invasive horticultural plants" (DLNR, 2001). According to this "it is urged that species on this list not be grown anywhere in the state of Hawaii".
It is classified as a Category 1 invasive exotic species in Florida: "when they are altering native plant communities by displacing native species, changing community structures or ecological functions, or hybridizing with natives" (FLEPPC, 2017).
This species shows tolerance to moderate frost, high temperatures, shading, grazing, damage, moisture, drought, salt and wind. It is fast-growing and long-lasting, forms root shoots and can form high and dense stocks; once established the species is difficult to eliminate. It produces a high number of highly-viable seed, the berries can be widely spread by birds. For this reason, in New Zealand it is listed on the National Pest Plant Accord list (NPPA, 2018). This contains plants which are banned from sale, distribution, display and propagation (see http:// www.mpi.govt.nz/protection-and-response/longterm-pest-management/national-pest-plant-accord/ and http://www.weedbusters.org.nz/weed-information/ligustrum-lucidum/59/).
The presence of both Ligustrum lucidum and Robinia pseudoacacia in this locality suggests a possible planting as bee pasture. Robinia pseudoacacia is a well-known and widespread honey plant and also the "Chinese privet" Ligustrum lucidum (like other Ligustrum species) is known as a good bee-tree (see for instance: https://www.urbanbees. co.uk/trees/trees.htm). This richly flowering plant has high ornamental value. At various times, planted specimens of this species were seen on La Palma, e.g. in San Andrés y Sauces (Chargo Azul, wayside of Camino el Cardal) or in Breña Alta (near Urbanisation La Grama, borders before supermarket). The occurrence at the foot of the Risco de Concepción does not give the impression of intentional planting. The plants are also not visible from the passing sidewalk and, unlike the clearly planted ornamental shrubs and palm trees, they are not cared for by green services. In 2005, the first author found a young, non-flowering plant (back then named cf. Dorycnium sp.) as epiphyte on Phoenix canariensis. This may be an indication of an unintentional introduction during the planting of the area. Because of the danger of falling boulders from the steeply towering rock face, the terrain was later fenced.

Lotus broussonetii
This record throws some new light on a previous finding of Bupleurum salicifolium R. Br. subsp. salicifolium in the same locality in 2014 (Otto & Verloove, 2018). It was also unintentionally introduced and most probably on the same occasion. Origin: originated in Europe from O. glazioviana and O. biennis. The hybrid and its parent species are today known from nearly all over Europe with the striking exception that Rostański et al. (2010) and Euro+Med (2006-2019) do not specify the hybrid for large parts of Southern Europe.
Degree of naturalization: ephemeral but potentially invasive.
The above-mentioned occurrence of Oenothera fallax is an example of a misguided "garden culture", namely the use of mostly foreign floral mixtures in the wild, e.g. on the roadside and in other places that supposedly need to be embellished. Next to the site of the Oenothera, on a several meter long strip of the unpaved edge of the road, locally common roadside species such as e.g. Echium plantagineum L., Bidens pilosa L. and Bromus madritensis L. but intermixed with Eschscholzia californica Cham., Linum usitatissimum L., another non-flowering Linum species, Lobularia maritima (L.) Desv., rosettes with crinkly leaves of Oenothera sp. (most likely the same taxon as above), Rudbeckia hirta L. and Salvia viridis L. are growing. These "exotics" are typical elements of many so-called flower mixtures (fragrance mixtures, butterfly meadows, etc.), applied with good intention but with the inhering danger of an expansionary spread, in this case especially of the Oenothera taxa.
One of several Oenothera rosettes was taken from the site and further cultivated in 2018 in Germany. It was identified as a very likely product of a cross of female O. biennis and male O. glazioviana by using the key in Murphy (2016 (Verloove, 2017).
Degree of naturalization: ephemeral but potentially weedy and invasive.
Reported as invasive from Australia, the Fiji Islands and the Hawaiian Islands (US Forest Service, 2019) and from Georgia and South Carolina (Swearingen & Bargeron, 2016).
In its natural distribution area P. notatum comprises several forms (Gates et al., 2004), mostly considered at the rank of botanical varieties, with different ploidy levels and sexual (2n) or apomictic (4n) reproduction. Many cultivars (see e.g. https:// www.invasive.org/gist/moredocs/pasnot01.pdf) have been developed and it is an important pasture grass and also used as lawn grass and for soil stabilization. Also, infra-and interspecific hybrids are known.
Degree of naturalization: long persisting after cultivation and apparently becoming strongly weedy.
Both parent species belong to Passiflora supersection Tacsonia (Juss.) Feuillet & J. M. MacDougal and are native to the Andean region of northwestern South America.
The cultigen Passiflora tarminiana is cultivated on La Palma for its edible fruit and as an ornamental (for more details see below).
Passiflora manicata is a wild species from intermediate elevations of the Andean region from Venezuela to Peru (1500-3000 m) with somewhat other ecological requirements than P. tarminiana: it grows there under drier conditions and in more open vegetation (G. Coppens d'Eeckenbrugge, pers. comm. 2018).
The fruits are hardly edible (toxic and psychotropic effects), but the plant is interesting because of its adaptation to warmer and drier environments, its resistance to some pests and it is used as rootstock for Passiflora tripartita (Juss.) Poir var. mollissima (Kunth) Holm-Niels. & P. Jørg (Ocampo et al., 2017).
About several spontaneous and artificial hybrids of wild and cultivated forms of the Tacsonia group New xenophytes from La Palma (Canary Islands, Spain), with emphasis on naturalized and (potentially) invasive species -Part 3 Figure 15. Passiflora manicata × tarminiana, Villa de Mazo, April 2017 (left and middle) and Passiflora tarminiana, Puntallana, August 2008 (right). Visible are the differences in the flower color and in the ratio of the lengths of hypanthium and sepals, as well as the different shape of the corona. P. tarminiana has only a single set of filaments, the corona is reduced to a single white tubercle ring. In the hybrid with P. manicata the corona filaments are inserted in three different series (photographs: R. Otto). has been reported by producers and several authors (Ocampo et al., 2017). Experimentally produced hybrids are also known from P. manicata and P. tarminiana (Coppens d'Eeckenbrugge, pers. comm., 2018).
It can be assumed that it is an artificial hybrid, most likely sterile or with only a slight set of fruit and introduced as a richly flowering ornamental plant. The exceptionally strong growth under dry and warm conditions is likely the visible legacy of P. manicata.
The hybrid character becomes clearly visible on the morphological features. Vegetatively, the plant resembles P. manicata, while the floral features are similar to those of P. tarminiana, except for the intermediate corona and floral tube length (Coppens d'Eeckenbrugge, pers. comm., 2018). These features are shown in Fig. 15.
This hybrid is probably identical with Passiflora ʻCoral Seaʼ. The latter is a hybrid cultivar of P. manicata and an unknown parent, known from California, where it is often cultivated along the coast (Rejmánek, 2009). Its description strongly recalls the hybrid of La Palma: "Extensively branching individuals can cover large trees. Plants are sterile, but persisting for a long time after cultivation" (see: http://bomi.ou.edu/ben/406/passiflora_figures.pdf). Particularly striking is the correspondence in the flower structure: "Hypanthium about the same length as sepals; corona filaments in three series, outer 0.6-1.0 cm, of filiform, violet elements, second series 0.1-0.3 cm, membranous, upper 1/2 split into filiform segments, white, third series 0.1 cm, membranous, white; corolla dark pink" (see: https://www.ou.edu/cas/botany-micro/ben/ben406. html). This is perfectly in line with the characteristic features of the La Palma specimen as shown in Fig. 15. Origin: cultigen, Andean highlands of tropical northwestern South America, widely cultivated at high elevations up to more than 3000 m (Coppens et al., 2001) throughout the Andean countries for a long time, introduced in many parts of the tropics worldwide and naturalized, e.g. in Australia, New Zealand and Hawaii.

Passiflora tarminiana
Degree of naturalization: ephemeral but potentially invasive.
Passiflora tarminiana is regarded as invasive from Hawaii and New Zealand (US Forest Service, 2019), and from Australia (Victoria) and California (CABI, 2019). Like P. caerulea and P. tripartita it belongs in New Zealand to the "banned plants" (NPPA, 2018).
One of the most commonly grown Passiflora species from the supersection Tacsonia was formerly known as P. mollissima (Kunth) L. H. Bailey. Due to morphological and genetic studies the currently accepted name for this taxon is P. tripartita var. mollissima. In 2001, the cultivar 'Banana Poka' of P. mollissima (Kunth) L. H. Bailey was recognized as an independent taxon and described as P. tarminiana (Coppens et al., 2001). This species is different from P. tripartita var. mollissima (and the other varieties of this species) by, e.g. smaller and readily deciduous stipules, a shorter hypanthium and a larger nectar chamber. To distinguish P. tarminiana, P. tripartita and the closely related P. mixta L. f. see the table in Coppens et al. (2001) and the key in Rejmánek (2009). The latter contains also P. caerulea L., P. edulis Sims, P. mixta L. and Passiflora ʻCoral Seaʼ.
In recent years, it has been found that many Passiflora mollissima occurrences worldwide in fact belong to P. tarminiana, e.g. the well-known and very problematic occurrence on Hawaii (Global Invasive Species Database, 2019). Also the indication of P. mollissima for La Palma (Otto & Verloove, 2016) is to be corrected to P. tarminiana (collection Nr. 14318, coll. 23.VIII.2008).
It is probably also listed for laurel forests on  (Silva et al., 2008). The flower color of P. tarminiana is usually lilac, very rarely also white (Coppens et al., 2001). Such white forms have also been observed in culture on La Palma. Origin: native of South Africa, cultivated in temperate areas worldwide as an ornamental and for the production of geranium oil, naturalized in Australia (Queensland Government, 2019) California, the Canary Islands, the Hawaiian Islands and New Zealand (US Forest Service, 2019).
Degree of naturalization: ephemeral but potentially invasive.
Invasive occurrences of the species are known from the Hawaiian Islands and New Zealand (US Forest Service, 2019). The occurrence of the species on Lanzarote is reported by Sanz-Elorza et al. (2004). Pelargonium capitatum is also a common ornamental plant in gardens and public green areas on La Palma. In some cases, e.g. occurrences on natural stone walls of banana plantations or on rocks near settlements, plantations and semiwild (and tolerated) occurrences can hardly be distinguished.  New to the flora of the Canary Islands. Spain, La Palma: Breña Alta, Camino Miranda, wall base on the roadside, 05.V.2012, R. Otto 19074 (pers. herb. RO); Sta. Cruz de La Palma, intra-urban part of the Barranco de las Nieves, dry gravelly riverbed, ruderal site, the occurrence probably originates from garden debris with ripe pods, young plant covers about one square meter of soil, 05.X.2017, R. Otto 22970 (pers. herb. RO); ibid., the occurrence has grown to a few square meters, plants overgrow partially young specimens of Abutilon grandifolium (Willd.) Sw. and Ricinus communis L., but mostly the plants grow close to the ground, with abundant dried fruits with germinable beans ca. 25 mm long and either white with irregular brownish to purple spots or vice versa, 29.III.2018, R. Otto 23100 (pers. herb. RO); ibid., abundant in fruit, 19.X.2018, R. Otto (pers. obs.); San Andrés y Sauces, San Andrés, Calle Iglesia, on the roadside between LP-104 and sports field, plants grow in a strong stock of Urochloa mutica (Forssk.) T. Q. Nguyen, with still unripe pods and pure white seeds ca. 30 mm long, ca. 75 m, 28.799374º N, 17.761908º W, 08.IV.2018, R. Otto 23173 (pers. herb. RO); ibid., above sports field, several specimens along the way, 22.X.2018, R. Otto (pers. obs.); ibid., Calle el Medio, small water gutter, seedlings, 31.X.2018, R. Otto 23445 (pers. herb. RO).

Phaseolus lunatus
Origin: the wild form (var. silvester Baudet) is native to the Andean region and Central America. Widely cultivated as var. lunatus in many types as a vegetable in warm temperate to tropical regions of the world.
Degree of naturalization: casual but possibly overlooked, wild occurrences of the short living perennial (mostly annual in cultivation) seem to persist for several years, possibly invasive.  Phaseolus lunatus cultivars are often cultivated in home gardens (especially on fences) and on walls of banana plantations of the lower zones in La Palma and the green pods and the seeds are used like those of Phaseolus vulgaris L.
P. lunatus may be sometimes confused (especially young or dwarf specimens and if without pods) with very similar forms of the variable P. vulgaris and perhaps also with non-flowering specimens of P. coccineus L. Another similar species is P. acutifolius A. Gray (Tepary bean), reported as naturalized from Gran Canaria in the cultivated, broad-leaved race var. latifolius Freeman (Verloove, 2013).
Four important beans of American origin exist in a huge number of cultivars and can be distinguished in the following key (modified from Hegi, 1924;Webb et al., 1988;Wu & Thulin, 2010).
Degree of naturalization: perhaps locally naturalized.
It most probably is a relatively rare and ephemeral weedy species in the Canary Islands, but it could also be overlooked sometimes or confused with one of the very similar other Portulaca taxa. New to the flora of the Canary Islands. Spain, La Palma: Breña Alta, above San Isidro, ca. 250 m before crossing LP-301 over Canal de Fuencaliente, roadside, two approximately one meter high bushes with numerous fruits, 665 m, 28.630620º N, 17.799618º W, 30.X.2018, R. Otto 23442 (pers. herb. RO, dupl. BR).

Pyracantha angustifolia
Origin: native to Southwestern China, cultivated as garden ornamental in temperate and subtropical regions worldwide and naturalized elsewhere, e.g. established in Madeira and Spain (DAISIE, 2019).
Pyracantha angustifolia is reported as invasive from Australia, French Polynesia, the Hawaiian Islands, New Zealand and South Africa (US Forest Service, 2019).
This up to four meter tall and wide, thorny evergreen bush has striking white flowers (up to 12 mm diameter) in downy corymbs and attractive brilliant yellow or orange colored fruits which are spread by birds. The leaves are ± narrowly oblong with rounded apex, the under surface is grey felted, the upper surface dark green and hairless. According to Webb et al. (1988) P. angustifolia can "be easily distinguished from all other Pyracantha sp. by the persistently tomentose petioles and leaf undersides". Origin: described from Mexico, known also from Central America and Colombia, introduced as perennial ornamental in many parts of the world and also used for creation of "green roofs".
Degree of naturalization: ephemeral but potentially invasive.
Feral occurrences of this species are known from several parts of the world (Roselló Gimeno et al., 2012), e.g. also from France and the Iberian Peninsula. It is reported as invasive from Japan (Mito & Uesugi, 2004).
For a description of the plant and the differences with the closely related Sedum lineare Thunb., see Roselló Gimeno et al. (2012).  Urochloa mutica (Forssk.) T. Q. Nguyen in Novosti Sist. Vyssh. Rast. 1966: 13 (1966  Origin: native to Africa. Cultivated as forage grass in the tropics worldwide and naturalized in warm temperate, subtropical and tropical regions. In Macaronesia known also from Madeira (Borges et al., 2008).
Known distribution in the Canary Islands: C (Verloove, 2013). Degree of naturalization: naturalized and highly invasive.
Worldwide the species is reported as invasive from many areas, e.g. from Australia, Central America, the Hawaiian Islands, Indonesia, Mauritius, New Zealand, the Philippines, South America (Colombia, Ecuador, Peru), Thailand and Vietnam (US Forest Service, 2019).
One can assume that the fast growing and largely creeping perennial grass was presumably introduced as a forage grass and is naturalized there for decades. As a consequence of its low tendency to bloom it was probably overlooked or confused with morphologically similar grasses like Pennisetum purpureum Schumach.
According to the first author's observations so far, the species occurs mainly in the humid northeast of the island. There are three obvious distribution centres, namely the communes of Sta. Cruz de La Palma, San Andrés y Sauces and Barlovento.
Here, the species occurs on disturbed sites practically from sea level to about 265 m, mainly at roadsides and their embankments and from there spreads to managed (e.g. banana plantations) and unmanaged cultivated land. Typical but mostly inaccessible are also occurrences on damp rock walls (e.g. coastal rocks), here often with several meters long far down hanging stolons, or occurrences in damp places in barrancos and ditches or in contact with (leaky?) water channels or water tanks.
The known populations are, at least in part, already large and dominant, nearly monospecific stands of some hundred, rarely up to more than thousand square meters. But many of them are only some square meters large, often easily overlooked populations in association and competition with other perennial, strong and tall grass species such as Arundo donax L., Pennisetum purpureum, Pennisetum setaceum (Forssk.) Chiov. and Paspalum urvillei Steud., once also with Urochloa maxima (Jacq.) R. D. Webster. As frequent accompanying dicots were seen e.g. Cardiospermum grandiflorum Sw., Foeniculum vulgare Mill., Kleinia neriifolia Haw., Opuntia sp., Ricinus communis L. and Rumex lunaria L. These higher-growing species compete best with the aggressive U. mutica.
The presence of non-flowering stands (flowering time on La Palma is November, December, January) and mowing alongside the streets make it sometimes difficult to see and/or identify the species. Confusion is possible especially with lean forms of Pennisetum purpureum, but this species has a much larger to 5 mm long ligule. P. clandestinum Hochst. ex Chiov. often has similarly hairy sheaths, but always hairless leaf nodes, a ligule about 2.2 mm long and leaves only up to 6 mm wide (vs. 10-15 mm). Somewhat similar in inflorescence is the cespitose Paspalum urvillei, but the spikelets of this species are clearly hairy, the ligule is membranous and up to 7 mm long and at the base of the adaxial leaf side there are striking, long hairs. Fig. 22 shows the essential characteristics of Urochloa mutica to distinguish the species from the other mentioned grasses, also in the vegetative stage.  Origin: probable native to Tropical Asia and Australia. Introduced into the tropics worldwide and naturalized in many parts of them.
Degree of naturalization: ephemeral but potentially invasive.
Urochloa subquadripara is a perennial, creeping species and willingly rooting at the nodes. It is reported as a troublesome weed and is also cultivated in some parts of the tropics as forage because of its drought tolerance. According to Teuton et al. (2004) it is "one of the most serious weed problems in the St. Augustine grass sod production in Florida and its presence increases production costs and lowers turfgrass quality".
The grass is reported as invasive for instance from the Fiji Islands, the Hawaiian Islands and New Caledonia Archipelago (US Forest Service, 2019) and from Texas (Hatch, 2010).
Our plant fits very well with the description given by Wipff & Thompson (2003). The lower palea is normally present in our collection, but we have also observed some spikelets with and without a lower palea in the same panicle.
According to Chen & Phillips (2006) our plant belongs to var. subquadripara. In dense lawns the prostrate grass is initially facile to overlook; later the flat lying leaves, partially mangled during mowing and then dried up, give the lawn a typical unattractive blotchy appearance due to its partial straw color (Fig. 23).
Urochloa subquadripara is sometimes included in U. distachya (L.) T. Q. Nguyen (see the discussion in CABI, 2019). Further occurrences in the Canaries are to be expected.    Ginovés et al., 2010).
Degree of naturalization: ephemeral but potentially invasive.
Volutaria tubuliflora is recently reported as invasive from the California desert and from the Chilean Atacama Desert (Harris et al., 2015;Mc-Donald, 2017). These authors report on the discovery of the species, its amazing expansion history in California and control measures. In contrast to the Canarian plants (all?) the American specimens have white flowers.
Recent molecular genetic studies (Calleja et al., 2016) have shown that the two Macaronesian endemic species V. bollei (Sch. Bip. ex Bolle) A. Hansen & G. Kunkel and V. canariensis Wagenitz, the African V. lippii (L.) Cass. and also V. tubuliflora are all well-separated species, despite some morphological similarities and in contrast with former presumptions (see e.g. synonyms).
According to Ma & Gilbert (2008) our plant belongs to the throughout the tropics cultivated E. c. subsp. cotinoides (syn.: E. cotinoides Miq.) with attractive leaves of conspicuous reddish brown color and with ovate-rounded leaf blade and subtruncate leaf base. The green-leaved subspecies cotinifolia in contrast has orbiculate and apically rounded leaf blades.
Spain, La Palma: San Andrés y Sauces, Los Sauces, Mirador de Llano Clara, under and near a high voltage mast on the slope, several vigorous plants, perhaps persistent from an earlier culture, growing together with Pennisetum thunbergii Kunth,467 m,28.800282º N,17 The presence of this species could not be confirmed subsequently, despite repeated searches. The occurrence of Urtica dioica is not surprising. Several times the first author saw potted individuals offered as medicinal plants on different markets of the island.

New to the flora of La Palma
Aloe arborescens Mill. (Xanthorrhoeaceae).
This species is frequently seen near settlements, on roadsides, embankments, garden waste dumps and similar disturbed places, often individuals of considerable size. Cucurbita pepo L. (Fig. 6B)  There is a risk of confusion with C. ficifolia and C. moschata in the case of dwarfish specimens as a result of dryness. For the differentiation of the Cucurbita species see the key under C. ficifolia.