2l6. ACANTHACEAE 505 



Fruit more or less terete or 4-angled. [Tribes RUELLIEAE and STROB- 

 ILANTHEAE.] 22 



18. Ovary-cells i-ovuled. Stigmas 2. Calyx 5-cleft or 4-parted, Flowers 



in axillar3^ clusters. Bracts oblong, about as long as the calyx ; bract- 



eoles smaller. — Species 8. Central Africa. Disperma C. B. Clarke 



Ovary-cells 2-ovuled. Bracts or bracteoles large 19 



19. Calyx-segments 4 owing to the complete or nearly complete union of the 



two anticous segments. Flowers solitary or in short lateral inflores- 

 cences. — Species 18. Tropics. (Under Petalidium Nees). 



Pseudobarleria T. Anders. 

 Calyx-segments 5, almost free 20 



20. Calyx-segments very unequal, the posticous much larger, bract-like. 



Inflorescences spike-like, composed of cymes. — Species 15. Tropical 



and South Africa. Some are used medicinally. {Aetheilema R. Br., 



Micranthus Wendl., Phaylopsis Willd.) .... Phaulopsis Willd. 



Calyx-segments nearly equal 21 



21. Stigma entire, capitate. Anther-halves blunt. Flowers in terminal false 



umbels. — Species i. Madagascar Zygoruellia Baill. 



Stigma unequally 2-lobed, fihform. Anther-halves pointed or tailed below» 

 Flowers solitary or in cymes. — Species 5. West and South Africa. 



Petalidium Nees 



22. (17.) Ovules 2 in each ovary-cell. Fruit contracted into a stalk, 2—4- 



seeded 23 



Ovules 3 or more in each ovary-cell 30 



23. Fertile stamens 2. Corolla-tube long and narrow throughout its length. 24 

 Fertile stamens 4 25 



24. Calyx divided nearly to the base. Corolla orange. Stigma capitate 



or oblong, more or less 2-lobed. Fruit ellipsoid, contracted into a 

 short stalk, usually 2-seeded. Flowers in heads, spikes, or panicles. 

 Bracteoles nearly as long as the calyx. — Species 5. Central Africa. 



Used as ornamental plants Lankesteria Lindl. 



Calyx divided to the middle or somewhat beyond. Corolla white. Stigma 

 entire, oblong-linear. Fruit linear, contracted into a long stalk, usually 

 4-seeded. Flowers solitary or few together in the leaf-axils. Bracteoles 

 much shorter than the calyx. — Species 4. South and East Africa. 

 (Under Calophancs Don) Chaetacanthus Nees 



25. Filaments free from the base 26 



Filaments united in pairs at the base and decurrent in the form of two 



ridges 27 



26. Calyx shortly toothed. Corolla blue, with a long tube. Disc very small. 



Flowers solitary, axillary. Bracteoles very small and narrow. — 



Species 2. Northern East Africa Satanocrater Schweinf. 



Calyx deeply divided. Flowers in racemes or panicles. Bracteoles large, 

 membranous. — Species 15. Central Africa. (Including Stylarthropus 

 Baill.) Whitfieldia Hook. 



