Watsonia palustris (Iridaceae), a new species from KwaZulu-Natal, South Africa and a revised key to allied summer rainfall species

Article history: Received 15 April 2016 Accepted 7 July 2016 Available online 15 July 2016 Edited by AR Magee Watsonia palustris is a wetland species restricted to marshy grassland in the vicinity of Greytown in central KwaZulu-Natal. Belonging to a group of species of eastern South Africa, Lesotho and Swaziland with pink flowers and a funnel-shaped perianth tube, it is characterized by its clumped habit, very narrow leaves, late summer flowering, partly herbaceous floral bracts, and shortly exserted anther filaments. Watsonia now comprises 53 species of corm-bearing geophytes restricted to southern Africa. © 2016 SAAB. Published by Elsevier B.V. All rights reserved.


Introduction
The genus Watsonia Mill. (Iridaceae), now comprising 53 species of cormous geophytes, is widespread in southern Africa and has two centres of diversity, in the winter-rainfall southwestern and in the summer-rainfall eastern part of the subcontinent, the latter area including eastern South Africa, Lesotho and Swaziland (Goldblatt, 1989). The genus is distinguished by firm-textured, sclerotic leaves with moderately to strongly thickened margins and main vein, and strongly 2ranked flowering spikes with firm-textured floral bracts that are either green and herbaceous or partly to completely dry and brown. As in most other genera of tribe Watsonieae, the three style branches are deeply divided for about half their length. Also typical of the tribe, the corms are lateral in origin, a character shared in Crocoideae only with tribe Tritoniopsideae (Goldblatt et al., 2006). Corm development in all other crocoids is axial.
Watsonia palustris is a new species restricted to the vicinity of Greytown in central KwaZulu-Natal, South Africa. It is typical of most eastern southern Africa species in the genus in its pink flowers with a funnel-shaped perianth tube, cylindric below and flared distally but stands out among them in its wetland habitat, relatively low stature, strongly clumped habit, late summer flowering, and floral bracts that are green in the lower half, becoming dry and brown only distally. The perianth tube is relatively short, 20-25 mm long with the lower part 13-15 mm long, and the anther filaments are exserted 3 mm from the perianth tube.
The new species is one of several new Iridaceae recently described from southern Africa (Goldblatt and Manning, 2015;Goldblatt et al., 2015aGoldblatt et al., , 2015bGoldblatt et al., , 2015cManning et al., 2016).

Materials and methods
The new species was described from plants collected in the field, where habitat details were noted. The following herbaria containing significant holdings of southern African flora were examined for additional collections: MO, NBG, NH, NU, PRE and SAM (abbreviations following Holmgren et al., 1990).

Taxonomy
3.1. Key to species of Watsonia from eastern southern Africa with pink perianth and funnel-shaped tube 1a Bracts entirely dry at flowering, uniformly brown or with pale veins, (10-)20-40 mm long, strongly overlapping and at least 2 internodes long; spike crowded with (10)20 to 60 flowers.
2b Plants forming clumps with stems more or less erect or inclined below.
1b Bracts usually partly green below, 5-30 mm long, sometimes overlapping but then either less than 2 internodes long or partly green below; spike crowded or relatively lax and with 3 to 30 flowers.