DiANTHERA. ACANTHACE.E. 27 



Order LXVIII. ACANTHACEiE. Juss. The Justicia Tribe. 



Calyx of 5 sepals, distinct or variously combined, persistent. Corolla mostly 

 2-lipped, sometimes one-lipped or somewhat equally 5-lobed ; the aestivation 

 twisted. Stamens 4 and didynamous, or often only 2, the anterior pair being 

 abortive or wanting. Ovary 2-celied, with two or more ovules in each cell; 

 the placentte in the axis : style filiform : stigma 2-lobed or entire. Capsule 

 2-celled, bursting elastically and locuhcidally, with 2 valves. Seeds roundish 

 or compressed, each usually supported by a retinaculum, or subulate process 

 of the placentae. Albumen none. — Shrubs or herbaceous plants, with opposite 

 simple leaves destitute of stipules. Flowers in spikes, racemes or fascicles, 

 rarely solitary, often showy. 



1. DIANTHERA. Gronov.; Lmw. (in part) ; Sclirch. gen. pi. 2& {\n ^^^.n). DIANTHERA. 



L From the Greek, dis, double, and anthcra, an anther ; each stamen appearing to be furnished with two anthers, in 



consequence of a separation of the cells.] 



Calyx 5-parted ; the segments equal. Corolla 2-lipped, not resupinate ; upper lip deeply 

 emarginate ; the lower deeply and equally 3-parted. Stamens 2 (the upper one and two 

 lower ones wanting), inserted into tlie tube of the corolla : anthers two-ceiled ; the cells 

 semioval, smooth, placed one above the other ; the upper one terminal and oblique ; the 

 lower parallel with the filament. Ovary two-celled, with two ovules in each cell : style 

 slender : stigma minute, slightly 2-cIeft. Capsule obovate, attenuated into a stipe at the 

 base, loculicidal. Seeds 2 in each cell, each supported by a hooked retinaculum. — Herbs, 

 with narrow entire leaves, and flowers in pedunculate heads. 



1. DiANTHERA Americana, Linn. Water Willow. 



Leaves linear-lanceolate ; spikes oblong, axillary, on elongated mostly alternate branches ; 

 flowers crowded. — Linn. sp. 1. p. 27. D. ensiformis, Walt. fl. Car. p. 63. Justicia 

 Americana, Willd. sp. 1. p. 92 ; Ait Kew. (ed. 2 ) 1. p. 38. J. linearifolia, Lam. ill. 1. 

 p. 41. J. pedunculosa, Miclix. fl. \. p.1 \ Pursh, Jl. \. p. \'i; Torr. fl. \. p. 17 ; Bot. 

 mag. t. 2;i67 ; Beck, hot. p. 285 ; Darlingt. fl. Cest. -p. 591. 



Root perennial, creeping. Stem 2 feet high, slender, straight, simple or a little branched 

 above, sulcate. Leaves 3-6 inches long and 4-8 lines wide, acute, attenuated at the base 

 into a short petiole. Peduncles 3-5 inches long. Spikes about an inch in length. Bracts 

 and segments of the nearly equal calyx lanceolate-linear. Corolla pale violet-purple, about 

 half an inch long, smooth : upper lip deeply emarginate ; lower of 3 nearly equal obovate- 

 oblong rounded lobes. Filaments as long as the tube of the corolla : anther-cells distinct ; 



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