Thesium section Hagnothesium, A. DC.

Zhigila, D. A., Verboom, G. A., Stirton, C. H. & Muasya, A. M., 2019, A taxonomic revision of Thesium section Hagnothesium (Santalaceae) and description of a new species, T. quartzicolum *, South African Journal of Botany 124, pp. 280-303 : 288-289

5.1. Key to the species in Thesium section Hagnothesium

1a Male and female plants similar, leaves subrotund, triangular or ovate, bracts and bracteoles scale-like, bracts shorter than flower …………………..…………..…………………...…… 2.

1b. Male and female plants dissimilar, leaves adpressed, linear or lanceolate, seldom acicular, bracts and bracteoles leaf-like, bracts longer than flower ………………….………………… 4.

2a. Plant sprawling, much-branched at distal portion, inflorescences crowded, fruit ovoid, substrate shale and sandstone ………………… ……………………… 5.2.3.5. T. microcarpum .

2b. Plant erect, sparsely branched at basal portion, inflorescences lax, fruit globose or truncated, substrate not shale or sandstone …... ………….………………………………….… 3.

3a. Stem sulcate in transverse section, fruit white when mature, elaiosome present, persistent perianth segments longer or equal to fruit, green when young but turns yellowish then orange at maturity, substrate sand dune or coastal beach sand …………………… 5.2.3.1. T. fragile .

3b. Stem terete in transverse section, fruit green when mature, elaiosome absent, persistent perianth segments shorter than fruit length, green when young and mature, substrate quart-silcrete ……………………………………………….……..………… 5.2.3.7. T. quartzicolum .

4a. Plant scabrid at all vegetative parts, midrib with hispid structures on leaves, bracts and bracteoles, perianth lobe 1–2 mm ……………… …………………………… 5.2.3.3. T. hirtum .

4b. Plant scabrid at leaf margins only, midrib without hispid struc-tures on leaves, bracts and bracteoles, perianth lobe 0.5–1 mm ………………….…………………………………….…. 5.

5a. Plant annual, 5–10 cm tall, rhizome stems present ………. …………... 5.2.3.6. T. minus .

5b. Plant perennial, 15–30 cm tall, rhizome stems absent ………………………......………… 6.

6a. Stem sulcate with verrucose edges, bracts and bracteoles with ciliated margins, perianth lobe segments distinctly uncinate, lobe mar-gins scabrid ……...……… 5.3.2. T. leptostachyum .

6b. Stem sulcate with glabrous or hispid edges, bracts and bracteoles with entire margins, perianth lobe segments not uncinate, lobe margins entire ……….…………………………… 7.

7a. Leaves linear-lanceolate in male plants, leaf margins not cartilag-inous, internode length 0.5–4 mm, midrib not raised, without hispid structures.………………. 5.2.3.2. T. fruticulosum .

7b. Leaves acicular in male plants, leaf margins cartilaginous, inter-node length 1–10 mm, midrib raised, with short hispid structures …………………………….… 5.2.3.4. T. longicaule .