A taxonomic revision of Elaeodendron Jacq. (Cassinoideae: Celastraceae) in Africa

The heterogeneous genuS;, Cassine L. s.l. is subdiv ided into smaller, more natural genera , following new evidence from macromorphology, palynology and anatomy. Elaeodendron Jacq. , one of the segregate genera , is here revised for Africa. The redefined genus Elaeodendron IS cosmopolitan, with consists of 30 to 40 species of shrubs and trees distributed in Africa, Asia, AustralaSia and central America, Eight species of EJaeodendron are recognized in Africa. A new combination , E. transvaaJense (Burtt Davy) R.H . Archer (:::: Cass;ne transvaaJensis) is proposed. The other species are EJaeodendron aquifolium (Fiori) Chiov" E buchananii (Loes.) Loes. , E. croceum (Thunb,) DC., E. matabeJiclIm Loes ., E. schJechterianum (Loes.) Loes. and E. zeyheri Spreng . ex Turcz. The correct application of the previously misapp:ied and confused name E. croceum is discussed.


Introduction
This paper emanates fro m a multi~disciplinary study towards a taxonomic revision of the southern African Cassinoideae (Archer & Van Wyk 1996a). It has long been a matter of dispute whether to treat Cas.\"ine L. in a wide sense (e.g. Ding Hou 1962; Koster~ mans 1(86), or to recognize a number of' segregate genera, including Elaeodem/ron Jacq. (e.g. Loesener in Die natOrlichen Ptlanzenfal11ilien, 1942a). Follow ing Archer (1990) and Archer and Van Wyk (1992. 1993a, 1993b, five distinct southern A friean genera, the African/Madagascar AlystroxJJlol1 and the cosmopolitan E/aeodel1dron, can be conclusively recognized on evidence frol11l11acrolllorphology. palynology, and anatomy . Our present concept of lassille s. str largely follows Loesencr (19420), Robson ( 1965Robson ( . 1966Robson ( . 1989 and Robson el al (1994) and necessitates many name changes back to the original basionyms in Elaeoc/endnm for Illost species of em'sine .d, from other parts of the world. Fortunately, most species have been wel! knowll under Elaeodendro}l, and in most cases correct combinations already exist. Approximately 40 species of Elaeodell~ droll can be recognized from central America, Africa and Australasia. Eight taxa are confined to Africa, excluding the Mascarenes and Madagascar, and are here revised . One species, E/aeodelldron orientale Jac q. , which was treated as a cultivated species in Flora Zambesiaca (Robson 1966), seems to exist in that Flo ra area as a single tree in the Mutare Botanical Garden, Zimbabwe. A synopsis of the known species of Elaeodendrol1 worldwide is in preparation and will be published elsewhere. Herbarium specimens cited here are arranged by the quarterdegree reference system of Edwards and Leistner (1971 ). One specimen is cited per quarter degree square. Localities north of the equator, or west of Greenwich are indicaled by the letters N or W after the longitude or latitude respectively. Codes following the geographical divisions of the Flora (?f Tropical East .·~ff'ica (Polhill 1988) have been added in the case of specimens cited for the latter region . ellipsoid, white to yellow; stone narrowly ellipsoid to ellipsoid, surface smooth or with grooves. Seeds brownish, narrowly ellipsoid, ovo id, flattened to triangular, postchalazal vascular bundles onen present, endosperm present; embryo erect with cotyledons flesh y, ell iptic or ovate.
E/aeodendron is one of the largest genera in the Celastraceae, cons isting mostly of shrubs or trees. An estimated 30 to 40 species occur in central America, Africa, Asia and Australasia. Some members are com mercially exploited or have potential for wood production.
The African species of Elaeodendron are more frequent in southern Africa and the eastern lowland parts of the continent. Three species. E. buchananii. E. matabelicuin and E. transvoalense, also extend to the drier parts of western trop ical Africa.
Much uncertai nty exists in recent li terature concerning the correct spelling and author citation of the name Elaeodendron (Archer & Van Wyk 1996b). Kostermans (1986) pointed out that Elaeodendl'um Murray has priority over Elaeodendron Jacq. f. , while most authors considered either Jacq. f. or Jacq. to be the correct author of the generic name. Archer an d Van Wyk (1996b) argue that Elaeadendron Jacq. ( 1782) is validly published as a plate wi th a n analysis and th at it predates both Murray ( 178 4) and Jacqu in f. (1787).
The latter genus is supported by a di stinctive pollen type with a rugu lose-reticulate exine structure (Archer & Van Wyk 1992). However, several tropical African and extra-African species are intermediate (in pollen structure and fl ower morphology) between Elaeodendron and Robson's concept of CrocoxylOI1.

Key to the African species of Elaeodendron
Elaeodendroll croceum occurs on the marg in s of coastal a nd montane fores t from near Ladi sm ith in the Weste rn Cape to northern KwaZulu-Natal in the east, as well as in isolated spots 1. a long the Mpu maln nga and Eastern Zimbabwe escarpm ent (F ig· ure 2). It is most abu nd ant and well known in the southern Cape forests w here it was o nce popular for its brig ht ye ll ow, durable wood. It is a lso natural ized and fairly abundan t on S t. Helena, hav ing sp read from pl antations of the spec ies es tab lis hed . Me lli s ( 1875) co nside red thi s species, whic h he pl aced under Olea? sr . and called wild olive. as very comlllon and 'one of lhe handsomest trees on the is land'. 1::. crOCClInI is distributed by frui t bats, Rameron Pigeons and even elephants (pers . obs.; Phillips 1925Phillips , 1927Hcrzig-S traschil & Robinson 1978) . Fl owering occ urs sporadi cally in s ummer. Fru it usually ripens about after a year. Thunberg (1794b) and Pappe ( 1858) recorded th e use of the tine and du rab le wood of E. crocellnI for the making of a ll kinds of furniture. building material , wagons as wel1 as buttercasks . Most parts of th e plant are poisonous and val ued for medicina l <Illd mag ica l p ro perti es (Watt & Breyer-Brandwijk 1962). Uaeodel1drol7 C1"ocel/m is a decorative g arden plant. Flavono id s <lncl trirerpe no id s fro m this species have been st udi ed by D rewes and M ash im byc (1993).
Llac()liem/roJl c.:rocellJII has been subj ec t to co ns ide ra l nomen· datura I co nfusion a nd name c hanges, evident in I ite rat ure a nd on herbari um sheets. Since Eckl on and Zeyher ( 1834/5), most ':llltho rs have m istaken the identity of Thunberg 's flex crocea. T he type specimen was carefully studied at UPS and the re can be no doubt as to its identity. it is likely that Thunberg encountered this species in th e Grootvadersbosch, near Swellendam (Thunberg 1794b). On a s ubsequent visit in 1774, Thunberg was di sappointed in again findi ng few trees in flower or fruit, but continued co llecti ng sterile speci men s, certai nly amongst others the present species. £/aeodendron crOCelll11 is freq uent in th e southern Cape, w hil e the species with w hich many authors have con fused it, E. =e)'heri (Cassine cracea allc/.), does not occu r Wl!st o f Po rt E lizabeth.
ElaeodencirolJ bllchanallii occurs in evergreen and riverine forest, deciduous woodland, grass land as well as on te rmitaria. The most widespread of the African species of Elaeodendron, it occurs in most cou ntries from west to east in Central Africa (F igure 4 ). This wide distribution perhaps accounts for the many synonyms recorded, Eas ily recognized in Elaeodendron by its dioecious flowers with petaloid stami nodes, a character shared w ith th e Centra l A merican E. xylocarpum (Vent.) DC.
E buchananii is very common in parts of Ugand a w here it is a possible source of timber production, The wood is fi ne-textured and hard , but can be worked to a smooth surface (Dale & Greenway 1961). Dale and Greenway (1961 ) and Verdcourt and T rump (l969) a lso reported it as being extremely poisonous to livestock. Verd court and Trump (l969) mentioned that in grassla nd the species is often sma ll and shru bby w ith in reach of stock with fatal results; however, it is frequently browsed by g iraffe , Elaeodendron kamenmense may we ll be regarded as a good

The two Zuric h speci mens were crypti ca lly annotated in
Loesener's hand and have been accepted as the ho lotypes of E.
12-16 x 13-15 mm; endocarp ± 2 mm thick, seeds dark-brown, elliptic, fl attened to triangular, 9.0 x 6.0 x 2.5 mm, embryo erect, widely elliptic.  Bot. 199X. 64(2) type specimen, the only flowering collection available to him . Flowers of additional specimens have now been examined and are ± identical to those of £. matabeliclll1l. The reported orange colour of the fruit (Robson 1965(Robson , 1966, instead of white or cream as in other species of Elaeodendron, is doubtful. Fruit of Torre 6717, cited by Robson ( 1965) was described as 'esbranquiyadas' (= whitish). In two additional specimens cited by Robson (1965), Comes e Sal/sa 1828 & 1871, the original Portuguese labels were replaced by new labels in French. It is likely the colour of fruit was incorrectly transtat,ed or that the colour of dried fruit, brown or reddish brown, was noted. It seems thus like ly that E. jruticOSItJ11 is merely a local variant of E. malabelicum.
There is a need for more fieldwork on the taxon in Mozambique. £. matabeliclll11 is possibly the species of Elaeodendron referred to in Watt and Breyer~Brandwijk (1962) involved in 'trials of ordeal' in Zimbabwe. It is also used as an aphrodisiac, for abdominal and chest pains, menorrhagia and diarrhoea in Zimbabwe (Gelfand el al. 1985). Malawi entire. Petals cream to green, oblong to ovate. 3 x 2 mm, sessil e. spreading, apex rounded. margin entire. Stamens initially erect, soon curving outwards with anthers almost touching sepals; filaments ± I mm long, arising from near centre of disc, anthers 0.5 mm long, extrorse. Disc entire, convex, thick and fleshy. Ovary 4-locular; style short to astylous; stigma inconspicuous. Fr uit drupaceous, spheroid to widely ellipsoid, yellowish, drying dark brown, 20-25 mm diam ., stone broadly elliptic, surface smooth with equal spaced grooves across the ends, 15-20 x 11 -14 mm diam. ; endocarp 2 rum thick.
Elaeodendron zeyheri is a relatively rare tree, only locally frequent in the Eastern Cape and some parts ofKwaZulu-Natal. The known distribution in the Eastern Cape, KwaZulu-Natal and one locality in Mozambique near the Mpumalanga-Swaziland border has been extended considerably by Mr. S. Venter who discovered several new records in the Northern Province (Figure 7).
Though listed as indeterminate in Hall el at. (1980), under the name Cassine eroeea auet., there appears to be no need for any conservation status at present. Flowering October to April. Fruiting December to June.
In the Eastern Cape and Northern Province bark is extensively collected for medicinal and magical purposes (Vernon 1994;personalobservations).
Until recently, the names Crocoxylon croeeum (Robson 1965(Robson , 1966 or Cassine croeea (Arnold & De Wet 1993) have been widely applied to this species. Ecklon and Zeyher were not only unaware of the true identity of Thunberg's flex crocellm when they published a taxonomic synonym, Elaeodendron capensis, in their Enumeratio Plan/arum, but they also chose the superfluous name Crocoxylon excelsum as the new name for E. CrOCelllJ1, therefore the type of Crocoxylon Eckl. and Zeyh. is E. croceum.
The generic description of Crocoxylon and the two specimens cited in the Enumeratio PlanlaruII1, however, clearly refer to the present species. This confusion has been perpetuated by most subsequent authors, adding to the confusion by misconstruing the characters and distribution of the two species (e.g. Von Breitenbach 1965, Coates Pal grave 1977. Most information in literature referring to Cassine crocea (hitherto often incorrectly referred to as Cassine papillosa) is applicable to Elaeodendron crocea and not E. zeyheri.

Selected specimens examined
£ laeodendron tral1SVaalellse is w idespread in southern A fr ica, being recorded from Zambia, Zimbabwe, Sout h Africa. Swaziland, Namibia. Botswana and Mozambique (Figure 8) where it occurs in woodlands a nd bus hvel d . occasio na ll y grow ing on termite mounds. In the KwaZu lu-Natal bush ve ld it is parti cularly conspi cuous, The Ingwavuma Dis trict in KwaZulu-Natal is named after the common Zu lu name of th e tree. Flowering December to April.
The bark of E. transvaalense is used extensively in Zulu traditional medicine (Hutchings 1996). On the Witswatersrand it is among the more popular items in trade on muti markets (pefs. camIn. V. Williams, Department of Botany, University of the Witwatersrand). Palmer and Pitman (1973) provide a recipe, recounted by Father Gerstner, for a tea made of bark. 11, a pel~ togynan and three pentacyclic triterpenoids have been isolated from the bark (Drewes et al~ 1991).
On account of its 3-merous flowers, unusual in the family Celastraceae, Loesener (l942b) placed this species as Pseudocassine in the Hippocrateaceae (a group with 3 stamens, although not 3merous).