Seed-micromorphology of 31 species of Ferocactus was investigated in order to determine whether it would suggest relationship where gross morphology did not. A remarkable correlation between characters of the hilum-micropylar rim (HMR) and fruit is reported and used to circumscribe two sections within subgenus Ferocactus. Bisnaga Orcutt is resurrected for the section with juicy fruits and shiny seeds with narrow HMR. F. robustus and F. flavovirens each have the least derived suite of characters within their respective sections. The most derived species have tabular-concave testa-cells and are grouped separately on this basis. The determination of species limits may also be aided by investigation of seed morphology.

Two new species of Aloe in the Saponariae group are described. Both occur in the northern mountains of Somalia; A. grisea in the Golis Range at Gaan Libah and Sheikh, and A. albovestita in the A1 Madu Range north and north east of Erigavo. A third new species is A. citrina from near Bulo Burti, extending into Kenya and Ethiopia. Aloe rigens var. glabrescens from the Las Anod—El Afwein area is raised to specific rank as A. glabrescens. All are diploid with 2n = 14 chromosomes.

The leaf-anatomy, pollen and cytology of mature plants and seedlings of Calibanus hookeri (Lem.) Trelease have been investigated and compared with that of Nolina, Dasylirion and Agave spp. The close relationship of Calibanus to Nolina and Dasylirion, and the dissimilarity of Agave, are confirmed. Calibanus leaves have deep stomatal grooves as in Nolina; the pollen grains are elliptic and monosulcate as in all the genera examined; and the karyotype (2n = 38) is similar to that of Nolina and Dasylirion. Successful pollination with one-year old refrigerated pollen, and improved seed-germination after removal of pericarp and testa, are reported.

Quaqua N.E. Br. is re-instated to accommodate the ‘hard-stemmed’ species of Caralluma occurring in the western Cape Province of South Africa. This group is revised to include 13 species, 9 subspecies and 2 varieties, and all necessary name combinations are made. Q. armata subsp. maritima and subsp. pilifera, Q. parviflora subsp. bayeriana and subsp. pulchra, and Q. incarnata var. tentaculata are described as new.

Echinopsis sensu latiore (Friedrich, 1974), including Echinopsis Zucc., Trichocereus Ricc., Helianthocereus Backbg., Pseudolobivia Backbg. p.p., Soehrensia Backbg. and Hymenorebutia Fric ex Buin., can be divided by seed characters into a limited number of sub-generic units. 48 SEM photos show representative seeds of group Ia = large northern Trichocerei, group Ib = Chilean Trichocerei, group IIa = southern Trichocerei including Helianthocereus and Soehrensia, group IIb = E. terscheckii and the ‘Pasacanas’, group IIIa = Echinopsis sensu stricto and Pseudolobivia pro parte, group IIIb = E. leucantha and F. chacoana, group IVa = E. aurea and related species, group IVb = Hymenorebutia. Chamaecereus silvestrii is attached here as group IVc (Echinopsis chamaecereus nom.nov.). Useful seed characters for this grouping were the size and the outline of the seed, the form and position of the hilum, the shape and size of testa cells and the microsculptural patterns of the testa caused by cuticular pleatings. Apart from nine new combinations, formal taxonomic changes, though suggested, are postponed until a monographic treatment brings additional facts.

The author introduces an annotated index of Mammillaria names to be completed in about four instalments. Authorities, places of publication, source data and essential synonyms are cited for recognized species and subsidiary taxa, followed by their Series classification, brief description, distributional data and discussion. Bibliographical sources for non-current names are also given. Selected species are illustrated.