| FLORA OF TROPICAL AFRICA. 
_ OrvdER XCVIIT. ACANTHACEA, (By I. H. Burkill and 
PY C. B. Clarke.) 
_ Flowers hermaphrodite, irregular. Calyx inferior, free ; segments 
§ or 4, nearly separate or sometimes more or less united. Corolla 
gamopetalous; tube campanulate or linear; limb 2-lipped, or 5-lobed, 
nore or less ]-sided. Stamens on the corolla, 4 didynamous, or 2 (with 
r without rudiments); anther-cells 2 or 1, at base rounded, acute, or 
Bailed, parallel at equal height, or one above the other more or less 
blique ; pollen ellipsoid (then usually ribbed or banded longitudinally), 
r globose (then often honeycombed, reticulate or echinulate) ; equatorial 
ores 2, 3, 6, closed by stopples, for protrusion of pollen-tubes. Ovary 
uperior, 2-celled ; ovules superimposed in 1-2 rows or solitary (2, col- 
ateral in Thunbergia, Afromendoncia), anatropous or obscurely amphi- 
ropous; style long, simple, minutely 2-fid. Capsule loculicidal, often 
lastically dehiscent (in Afromendoncia a drupe) ; seeds usually nearly as 
pany as ovules, held up on the thickened up-curved outgrowth of 
she funicle, the retinaculum (except in the first 5 genera), compressed 
terally ; albumen 0 (except in the Velsonieew).—Herbs or shrubs, 1 or 
}arborescent. Leaves opposite; stipules 0. Inflorescence various, in 
trobiliform spikes, or heads, or lateral or terminal clusters; or flowers 
‘gjitary, panicled or axillary; bracts large or small or 0. 
‘+ An Order consisting of 140 genera and 2000 species, abundant in the tropics, 
_tequent in temperate climates, absent from Alpine and Arctic regions. 
|. Inthe tribe Ruelliew, there is frequently a large anterior bract to the sessile flower, 
4d 2 lateral bracteoles between this and the flower. In the Hujusticiew, it is fre- 
epently so difficult to distinguish the bract from the bracteoles that little use is made 
_} the character for descriptive purposes. In several cases, as in Phaylopsis, there are 
owers subsessile in the axil of each (apparent) bract ; in such a case in the present 
rk each flower is then considered to be strictly without bract or bracteole, and the 
»ract ’? enclosing an inflorescence is termed frequently a floral leaf. 
|This terminology is merely descriptive; for it very frequently happens that a 
ute shoot, sometimes bearing a flower, appears inside the lateral bracteole. Also 
VOL. V. B 
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