Compilation
Crassula retrorsa

This species is similar to C. alba Forssk. (= C. abyssinica A. Rich.) The two can be distinguished as follows (some characters not included in the key are mentioned here):Indumentum relatively sparse, composed of relatively short papillae; sheaths of lower leaves 1 (rarely less)-3 cm. long; sepals usually up to half as long as corolla, not denticulate, either entire or with obtuse marginal papillae; petals smooth and indistinctly mucronate; anthers suborbicular, 0·3-0·5 mm. longC. vaginataIndumentum relatively dense, composed of longer papillae; sheaths of lower leaves usually less than 1 cm. long; sepals longer than 1/2-up to as long as corolla, the margins acutely denticulate; petals sometimes subtuberculate-scabrous on the upper part of the outer surface, distinctly mucronate; anthers oblong, 0·5-1 mm. long C. albaMany specimens of C. vaginata from S. Africa have broader and denser leaves than is usual in the F.Z. area, as well as more frequently glabrous or subglabrous stems and sepals lacking marginal papillae. However, similar leaves have been found in other regions, as in the Cameroons (C. mannii), Sudan, Uganda, Tanzania (C. abyssinica var. ovata), Zaire and Angola; and they occur here and there in the F.Z. area. Sepals without marginal papillae are also known in both F.Z. specimens and ones from other tropical countries.As can be seen from the synonymy many varieties have been distinguished. However, it seems quite impossible to separate infraspecific taxa within C. vaginata, based on such characters as stem stoutness, leaf size and shape, presence, absence or quantity of indumentum or occurrence of marginal papillae on sepals, because they vary independently.C. vaginata was described with “flores flavi”. Unless it was noted by the collector, it is often impossible to decide on the original petal colour; nearly all specimens have reddish- to blackish-brown corollas, although they were ± white at anthesis. However, yellow corollas have never been mentioned by collectors in the F.Z. area. Torre & Correia 15377 (LISC) from Mozambique has red corollas.The many specimens seen from Mulanje Mt. (Malawi) have a characteristic habit, being only (2·5)4-10(12) cm. high, with the rosulate leaves narrowly linear and more persistent than usual, and the cauline leaves similar. They seem to represent a dwarf altitudinal form of exposed places and thin soil over rock. As intermediates occur at lower altitudes between them and more robust plants of the normal form, it is advisable not to recognise them formally.Several specimens from the Chimanimani Mts. region of Zimbabwe (E) and Mozambique (MS), for example Goodier 177 (SRGH), Phipps 647 (K; SRGH), Hall 429 (SRGH) and Pereira, Sarmento & Marques 1315 (LMU) are distinctly low-growing, with small, relatively broad leaves connate for not more than 5 mm. at the base, and with a long, dense, stem indumentum. They may be hybrids between C. vaginata and C. setulosa, of which the latter also grows in this area,