18. (10.) Stamens 1-2. Perianth-segments 3-5, membranous, woolly, 1-nerved. Herbs.--Species 1. Tropics. =Nothosaerua= Wight Stamens 4-5. 19 19. Outer perianth-segments densely clothed with silky hairs, faintly 3-nerved. Style slender. Shrubs.--Species 2. Northern East Africa (Somaliland). =Chionothrix= Hook. fil. Outer perianth-segments glabrous or scantily hairy, with 3 strong ribs. Flowers greenish.--Species 15. Central and South East Africa. (Including _Psilostachys_ Hochst.) =Psilotrichum= Blume [Illustration: AMARANTACEAE. _FLOW. PL. AFR._ _Pl. 41._ J. Fleischmann del. Achyranthes angustifolia Benth. _A_ Flowering branch. _B_ Branch of the inflorescence. _C_ Flower cut lengthwise.] [Illustration: NYCTAGINACEAE. _FLOW. PL. AFR._ _Pl. 42._ J. Fleischmann del. Pisonia aculeata L. _A_ Branch with inflorescences. _B_ Male flower. _C_ Female flower. _D_ Female flower cut lengthwise. _E_ Fruit. _F_ Fruit cut lengthwise. _G_ Group of fruits.] 20. (9.) Spurious staminodes interposed between the stamens. 21 Spurious staminodes none. 26 21. Spurious staminodes small, entire. Ovary hairy. Either perianth clothed with long silky hairs or leaves alternate. 22 Spurious staminodes usually quadrate and fringed, more rarely narrow, but then perianth not clothed with long silky hairs and leaves (as nearly always) opposite. 23 22. Ovary with a horn-like appendage.--Species 6. South and Central Africa. (Under _Sericocoma_ Fenzl). =Cyphocarpa= Lopr. Ovary without a horn. (See 14.) =Sericocoma= Fenzl 23. Partial inflorescences consisting of 3 fertile flowers without sterile ones. Perianth hairy. Erect shrubs.--Species 4. South and Central Africa. (Under _Sericocoma_ Fenzl or _Cyphocarpa_ Lopr.) =Sericocomopsis= Schinz Partial inflorescences consisting of fertile and sterile flowers, or of 2 fertile ones only. 24 24. Stem woody, climbing. Leaves ovate. Sterile flowers reduced to long tufts of hairs. Perianth glabrous. Spurious staminodes narrow, entire or toothed.--Species 2. Equatorial regions (Uganda and Cameroons). =Sericostachys= Gilg & Lopr. Stem herbaceous or woody at the base only, erect or ascending. Sterile flowers usually reduced to spines. Spurious staminodes usually broad and fringed. 25 25. Perianth-segments thickened and hardening at the base, yellow or red. (See 17.) =Centema= Hook. fil. Perianth-segments not hardening.--Species 15. Tropical and South Africa. Some are used in medicine. (_Desmochaeta_ DC.) =Cyathula= Lour. 26. (20.) Partial inflorescences consisting of 2 fertile flowers without sterile ones, and arranged in globose heads. Perianth white, with silky hairs. Ovary hairy. Shrubs.--Species 1. German South-West Africa. (Under _Marcellia_ Baill., _Sericocomopsis_ Schinz, or _Sericocoma_ Fenzl). =Leucosphaera= Gilg Partial inflorescences consisting of fertile and sterile flowers, the latter sometimes reduced to bristles or spines. 27