E. Retief

Palynology of southern African Boraginaceae: The genera Lobostemon, Echiostachys and Echium

The tribe Echieae of the subfamily Boragineae (Boraginaceae) is represented in southern Africa by the genera Lobostemon Lehm, and Echiostachys Levyns, endemic to the south‐western Cape region, and two species of Echium L., E. plantagineum L. and E. vulgare L., both introduced weeds of cultivation. Pollen of all these genera was studied and only one pollen type is recognized. Grains are tricolporate, heteropolar and triangular in equatorial view; ora more or less circular and situated towards the broader pole; tectum reticulate with densely spaced lumina; suprateetal nodules are situated at margins of lumina. The P/E ratio varies from 1.08 to 1.63. Genera of the Echieae are sometimes placed in the tribe Lithospermeae. A comparison of the pollen of the studied genera with that of Lithospermum, confirms that the tribe Echieae should be retained. Pollen of Lithospermum is 6–8‐zonocolporate, usually more or less isopolar and with colpi rhombic in outline. The presence of zygomorphic flowers and absence of calc...

A new species of Rhoicissus (Vitaceae) from Sekhukhuneland, South Africa

Rhoicissus sekhukhuniensis Retief, Siebert & A.E.van Wyk, a rare new species from South Africa, is described, illustrated and compared with other members of the genus. It is a scandent shrub, rarely a robust climber, the young growth with a dense indumentum of reddish brown hairs. The species is closely related to the simple-leaved R. tomentosa (Lam.) Wild & R.B.Drumm., from which it can be distinguished by trifoliolate leaves with coarsely toothed margins. Pollen grains are tricolporate with a reticulate tectum. R. sekhukhuniensis is endemic to the Sekhukhuneland region, a centre of plant endemism associated with ultramafic rocks (mainly norite, anorthosite and pyroxenite) of the Eastern Bushveld igneous Complex.

A new species of Cyphostemma (Vitaceae) from South Africa

Cyphostemma rubroglandulosum Retief & Van Wyk, a new species from South Africa, is described, illustrated and compared with other members of the genus in southern Africa. It is a climbing, succulent herb with conspicuous, red, multicellular, glandular hairs on the stems, leaves and inflorescences. The combination of glandular hairs, 3-foliolate leaves, and fruits with scattered, multicellular hairs distinguishes it from all other members of the genus in southern Africa. Pollen grains are 3-zonocolporate with a reticulate tectum; the closely spaced pores differ in shape and size. Associated with forest, C. rubroglandulosum is endemic to the Pondoland Centre, an acknowledged centre of endemism associated with Natal Group Sandstone (Msikaba Formation) in southern KwaZulu-Natal and parts of the adjacent Eastern Cape Province.

The genus Amsinckia Lehm. (Boraginaceae) in southern Africa

The genus Amsinckia (Boraginaceae / Boraginoideae / Eritrichieae) comprises ± 15 species, all native to the western United States, with California the centre of diversity. In southern Africa only A. retrorsa Suksd., most probably introduced by means of wheat seed, has established itself in the Northern and Western Cape, sporadically also occurring in other parts of the country. It is an annual herb characterised by small, yellow or orange-yellow flowers borne in terminal, cymose inflorescences with cymules helicoid, elongating and uncoiling in the fruiting stage, typical of Boraginaceae. A. retrorsa has retrorse hairs on the stems and the nutlets are ovoid-trigonous, rugose, tuberculate and verrucose with Verrucae minutely muricate. These characters distinguish A. retrorsa from other members of the family in southern Africa. The 6-heterocolpate pollen grains of A. retrorsa show similarity to those of Heliotropium L. (Boraginaceae, subfamily Heliotropioideae), but the presence of a gynobasic style, not terminal as in Heliotropium, still places A. retrorsa in Boraginaceae s.l., subfamily Boraginoideae. Diagnostic characters, a full description, various illustrations and a distribution map of A. retrorsa are given.

Cynoglossum obtusicalyx (Boraginaceae), a new species from South Africa

Cynoglossum oblusicalyx Relief & Van Wyk, a new species From the southern Karoo, is described and illustrated. It is a perennial, softly hairy herb with relatively large flowers and the calyx lobes markedly obtuse to truncate; the nutlets are evenly covered with glochidia (hooked bristles). Pollen grains are 6-heterocolpate, with compound and simple colpi linked. The new species occurs on screes in relatively arid mountainous surroundings, whereas other southern African members of the genus are mainly found in the higher rainfall areas of the Grassland Biome or along the east coast to the Cape Peninsula.

A new species of Raphionacme (Periplocaceae) from the Orange Free State

Raphionacme dyeri Retief & Venter, a new species from the Orange Free State, is described. The species is closely related to R. zeyheri Harv. The yellowish green inner surface of each corolla lobe with a purple or magenta ‘V’ marking on the upper half, distinguishes R. dyeri from all the other Rtaphionacme species.

A New Species of Pavetta (Rubiaceae) from South Africa

Abstract.  Pavetta glaucophylla Retief, S. J. Siebert & A. E. van Wyk, a new species of the Rubiaceae (Ixoroideae) from South Africa, is described and illustrated. A member of Pavetta L. subg. Pavetta, it has a restricted range and is near endemic to the Sekhukhuneland Centre of Endemism. Hitherto P. glaucophylla has mainly been confused with P. zeyheri Sond., from which it differs in being a taller plant with larger, blue-green leaves in living condition instead of dark green to gray-green leaves and flowers in which the calyx lobes are 0.5–0.75 mm long and triangular-ovate, and 1.25–2 mm long and not triangular-lanceolate, as in P. zeyheri.