838 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



114. ACANTHACEAE. Acanthus family 



Plants perennial, herbaceous or shrubby; stems commonly quad- 

 rangular; leaves opposite, simple, entire; inflorescences usually 

 bracteate, cymose, racemose, spicate, or the flowers solitary; corolla 

 more or less irregular; anther-bearing stamens 2, or 4 in unequal 

 pairs; ovary superior, borne on a disk; fruit a 2-celled, elastically 

 dehiscent capsule. 



Many plants of this family are cultivated as ornamentals, notably 

 the European Acanthus mollis and the South African climber, Thun- 

 bergia alata. 



Key to the genera 



1. Flowers in dense terminal spikes, closely subtended by imbricate bracts, these 



cuspidate or aristate at apex; plants herbaceous; stamens 2 (2). 



2. Plant subcaulescent, with all of the well-developed leaves basal or nearly so 



and short lived; floral bracts obscurely veined (only the midrib at all 



conspicuous) , with scarious margins prolonged into 2 winglike teeth on 



each side of the terminal awn; corolla limb purple 1. Elytraria. 



2. Plant caulescent, the steins with several pairs of well-developed leaves; floral 



bracts prominently 3-ribbed and often with 2 smaller additional veins, 

 not scarious-margined; corolla limb pale yellow, often tinged or spotted 



with purple 7. Tetramerium. 



1. Flowers not in dense spikes, or not closely subtended by imbricate bracts (3). 



3. Bracts subtending each flower in pairs, thin, valvelike, closely compressed, 



nearly orbicular, very different from the foliage leaves- 8. Dicliptera. 

 3. Bracts not in valvelike pairs and not very different from the foliage leaves 

 except in size (4) . 

 4. Corolla convolute in the bud, only slightly irregular; stamens 4, the fila- 

 ments much longer than the 2-celled anthers; stigma linear; plants 

 herbaceous (5). 

 5. Flowers axillary, solitary or in few-flowered clusters, sessile or nearly so; 

 corolla less than 3 cm. long; anthers acutish, mucronulate. 



2. Dyschoriste. 



5. Flowers in loose terminal panicles, mostly distinctly pedicelled; corolla 



more than 3 cm. long; anthers obtuse, muticous 3. Ruellia. 



4. Corolla imbricate in the bud, strongly irregular, bilabiate (6). 



6. Stamens 4, the anthers 1-celled, pubescent, as long as [or longer than the 



filaments; stigma somewhat funnelform, small 4. Berginia. 



6. Stamens 2, the anthers 2-celled, much shorter than the filaments; stigma 



minute, capitate or somewhat flattened (7). 



7. Anther cells inserted at the same height or very nearly so, parallel, 



contiguous, muticous; plants shrubby or suffruticose (8). 



8. Corolla very open, 1 to 1.5 cm. long, the lobes about twice as long as 



the tube 5. Carlowrightia. 



8. Corolla tubular-funnelform, more than 2 cm. long, the lobes shorter 



than the tube 6. Anisacanthus. 



7. Anther cells inserted at different heights (9). 



9. Corolla white, the tube very slender, 3 cm. long or longer; plant 



herbaceous or suff rutescent ; leaf blades lanceolate. 



9. SlPHONOGLOSSA. 



9. Corolla red; plants shrubby; leaf blades oval or ovate (10). 



10. Lower cell of the anther without a conspicuous basal callus, 



merely mucronulate 10. Jacobinia. 



10. Lower cell of the anther with a conspicuous whitish basal callus. 



11. Beloperone. 

 1. ELYTRARIA 



Plant herbaceous; scapes numerous, decumbent or spreading, en- 

 tirely covered with closely imbricate, glumelike bracts; floral bracts 

 like those of the scapes but larger, ciliate with short soft hairs, other- 

 wise glabrous, bluish green; calyx 4-parted; corolla imbricate in the 

 bud, narrowly funnelform. 



