30 NATURAL HISTORY OF PLANTS. 
at their apices, surmount the ovaries. The fruit, accompanied 
at its base by the persistent calyx, is composed of two orbicular 
compressed achenes, smooth or rugose, touching each other 
within by a flat surface, but separating easily. Their thick solid 
pericarp hollowed by vacuoles, thinner within where there are 
apertures (figs. 37,38), encloses a vertical seed (figs. 39, 40); 
its membranous coats covering an annular embryo with inferior 
radicle, enveloping a farinaceous albumen. Limeum consists of 
annual or perennial herbs of Asia and tropical Africa. The 
leaves are alternate, narrow, simple, entire or ciliate, and exstipulate. 
The flowers are arranged in axillary or subterminal cymes some- 
times united in racemes of terminal cymes, when bracts replace 
the ordinary leaves at the apex of the branches. Ten species have 
been described! With the same vegetative organs and floral 
organization, Semonvillea,? of which one Cape species is known, and 
another of Western Tropical Africa, has been taken for the type of 
a particular genus, because the edges of the achenes expand into 
an orbicular wing, transforming them into samaras. We only make 
it a section of the genus Limeum. 

II. BARBEUIA SERIES. 
Barbeuia’ (figs. 41-43) has regular, hermaphrodite, apetalous 
flowers. Upon the slightly convex receptacle are inserted five 
sepals, a little unequal as to size and thickness, and arranged in 
quincuncial prefloration in the bud. More internally, upon the 
slightly projecting ring of the receptacle are inserted an indefinite 
number of stamens, each formed of a free filament and a bilocular,* 
introrse, sagittate anther, dehiscing by two longitudinal clefts. The 
gynæceum is free and superior, formed of a bilocular’ ovary, sur- 

1 FENZL, in Ann. Wien. Mus., i. 341.— Harv. Gen., n. 6843,—H. BN., in Adansonia, iii, 312 
et SOND., FI, Cap., i. 152. t. 6. 
2 J. Gay, in Bull. Féruss., xviii. 412.— ENDL, 4 Its cells are independent at their two ex- 
Gen., n, 5259.—F Enz1, in Dec. Mus. Vindob., n.  tremities. 
48.—Moa., Prodr., xiii. p. 2, 19. —Hoox., Icon., 5 The separating partition of the cells de- 
t. 587.—B. H., Gen., 859, n. 21. scending from the apex of the ovary to its base, 
3 Dur.-Tu., Gen. Nov. Madag., 6.—EnpDt., does not here adhere to the ovary wall. 
