628 Flora of the Malayan Peninsula. 



Family LXXXIX.— ACANTHACE^. 

 [By C. B. Claeke.] 



Herbs or shrubs, or twining plants {Thunhergia). Leaves opposite, 

 often unequal, in Polytrema sometimes pseudalternate ; stipules 0. In- 

 florescence various ; spikes strobilate or heads or cymose or flowers 

 solitary ; bracts and prophylla large, small or 0. Flowers 2-sexual, 

 irregular. Calyx inferior ; segments 5 or 4, nearly free or more or less 

 united. Corolla gamopetalous ; tube campanulate or linear ; limb 

 2-lipped or 5-lobed, more or less 1-sided. Stamens on the corolla 

 4 didynamous, or 2 (with or without rudiments) ; anther-cells 2 or 1 ; 

 pollen ellipsoid (then usually ribbed or banded longitudinally) or globose 

 (then often honeycombed or echinulate). Ovary superior, 2 - celled ; 

 ovules 2 to 1, or several, superimposed in vertical rows (or 2 collateral 

 in Thunhergia) ; style long, simple, minutely 2-fid. Capsule loculicidal, 

 often elastically dehiscent ; seeds usually nearly as many as the ovules, 

 held up on rigid curved retinacula (outgrowths of the funicle) ; albu- 

 men 0. — DisTEiB. Species 2000, throughout the warmer parts of the 

 world. 



This Family is specially characterized by the retinacula and the seeds placed in a 

 vertical line ; this character fails in the first two Subfamilies. The plants of Sub- 

 family II. Nelsonioide^ are frequently mistaken for those of Sceophulaeiace^, from 

 which they differ by the seeds being superimposed vertically. 



Conspectus of the Subfamilies, Teibes, and Geneea. 



Subfamily I. Thdnbekgioide^. Seeds 4 to 2 in the capsule 



without retinacula. Twiners . . . . . . 1. Thunbergia. 



Subfamily II. Nelsonioide^. Seeds 8 to 16, vertically super- 

 imposed in 2 rows in the capsule on small soft papillae (not 

 on hard curved retinacula). Herbs small or of very moderate 

 size : — 



Stamens 2 . . . . . . . . . . 2, Nelsonia. 



Stamens 4 : — 

 Flowers in spikes, racemes, or panicles . . . . 3. Staueogyne. 



Flowers axillary . . . . . . . . 4. Caedantheea. 



Subfamily III. Ruellioide/E. Eetinacula present. Corolla-lobes 

 contorted in the bud : — 



Tribe 1. Buelliin^. Capsule with more than 4 seeds, which 

 are hygroscopically shaggy on the margin : — 



Pollen honeycombed. Flowers axillary. Capsule clavate 7. Ruellia. 

 Pollen echinate. Capsule seed-bearing from the base . . 8. Apobuellia. 

 Pollen ellipsoid, with many longitudinal ribs. Capsule 

 hardly stalked : — 



