Xerocladia Harv. in W.H. Harvey & Sonder, Fl. Cap. 2: 278. 1862.
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https://dx.doi.org/10.3897/phytokeys.240.101716 |
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https://treatment.plazi.org/id/7A38C697-BF0C-1E60-952B-16E9A89DE063 |
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scientific name |
Xerocladia Harv. in W.H. Harvey & Sonder, Fl. Cap. 2: 278. 1862. |
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Xerocladia Harv. in W.H. Harvey & Sonder, Fl. Cap. 2: 278. 1862. View in CoL
Figs 138 View Figure 138 , 139 View Figure 139 , 140 View Figure 140
Type.
Xerocladia zeyheri Harv. [= Xerocladia viridiramis (Burch.) Taub.]
Description.
Small, rigid, densely and intricately much-branched shrub to 1 m (Fig. 138A View Figure 138 ), the branches often somewhat zig-zag, shoots mid- to olive-green, sub-striate; brachyblasts absent. Stipules spinescent, in pairs, recurved (Fig. 138G View Figure 138 ). Leaves small, bipinnate; petiole with a stipitate reddish-brown gland immediately below insertion of pinnae, unijugate (Fig. 138G View Figure 138 ); leaflets 6-12 pairs per pina, sub-opposite, usually with a small reddish-brown gland at the base of each leaflet. Inflorescences solitary capitula, in axils of leaves (Fig. 139A View Figure 139 ). Flowers sessile, dark maroon, young filaments reddish-maroon (Fig. 139A View Figure 139 ); sepals 5, valvate, free almost to the base; petals 5, valvate, free except at base; stamens 10, free, anthers with a minute, caducous, apical claviform gland arising from the connective; pollen in tricolporate monads, pores with costae, exine smooth, perforated, columellae present; ovary shortly stipitate, stigma truncate. Fruits sessile, indehiscent, broadly falcate-ovate to semi-orbicular, compressed, the lower suture arched and winged, 1 (2)-seeded, valves coriaceous, chestnut- to reddish- or purplish-brown when ripe (Fig. 139H View Figure 139 ). Seeds sub-circular to elliptical, smooth, pleurogram present, U-shaped, testa hard.
Chromosome number.
Unknown.
Included species and geographic distribution.
Monospecific ( X. viridiramis ), endemic to arid parts of Namibia and Namaqualand in southern Africa (Fig. 140 View Figure 140 ).
Ecology.
Arid scrubland in sandy river soils, on riverbanks, alluvium and saline flats.
Etymology.
From Greek, xero - (= dry) and - cladion (= branch), in reference to the dense branching habit typical of small shrubs in arid climates.
Human uses.
Unknown.
Notes.
Xerocladia has long been thought to be closely related to the former Prosopis s.l. ( Catalano et al. 2008) with which it shares arid ecology and characteristic green photosynthetic shoots. It is robustly supported as sister to Strombocarpa with which it shares similar armature in the form of spinescent stipules, and unijugate leaves. However, despite these obvious similarities, Xerocladia is a highly distinctive and easily recognised genus, and its small reniform, flattened, indehiscent, 1 (2)-seeded winged fruits are unique within Mimoseae (Fig. 139H View Figure 139 ).
Material referred to under the name Xerocladia pampeana Speg. from Argentina, shows clear affinities to the genus Prosopidastrum Burkart, as suggested by Palacios and Hoc (2005).
Taxonomic references.
Dyer (1975); Ross (1975a); illustration Fl. Southern Africa 16: 131.
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