-ACANTHACEJ5. (ACANTHUS FAMILY.) '297 



placcntcB. — Flowers much bracted. Calyx 5-cleft. Style thread-form: 

 stigma simple or 2-cleft. Pod loculicidal, usually flattened contrary to the 

 valves and partition. Cotyledons broad and flat. — Mucilaginous and 

 slightly bitter, not noxious. A large family in the tropics, represented in 

 the Northern States only by two genera. 



1. DIAIVTIIl^RA, Gronov. Watee-Willow. 



Calyx -B-parted. Corolla deeply 2-lipped ; the upper lip erect, notched ; the 

 lower spreadmg, 3-parted. Stamens 2 : anthers 2-colled, the cells placed one 

 lower down than the other. Pod obovate, flattened, contracted at the base into 

 a, short stalk, 4-seeded. — Perennial herbs, growing in water, with narrow and 

 entire leaves, and purplish flowers in axillaiy peduncled spilces or heads. (Name 

 from Sis, double, and avOr^pa, anther; the separated cells giving the appearance 

 of two anthers on each filament.) 



1. D. Ameiicana, L. Leaves linear-lanceolate, elongated ; spikes ob- 

 long, dense, long-peduncled. (Justicia pedunenlosa, Michx.) — Borders of 

 streams and ponds, N. W. Vermont to Wisconsin, Virginia, and southward. 

 July- Sept. 



2. DIPTERACASTTHUS, Nees. (Ruei.lia partly, £.) 



Calyx deeply 5-cIeft. Corolla funnel-form, the spreading ample limb almost 

 equally and regularly 5-cleft. Stamens 4, included, didynamous : cells of the 

 somewhat an-ow-shaped anthers parallel and nearly equal. Pod somewhat flat- 

 tened, and stalked at the base, 8 - 12-seeded. Seeds with a mucilaginous coat- 

 ing. — Perennial herbs, not aquatic, with ovate or elliptical nearly entire leaves, 

 and lai-ge and showy blue or pui-ple flowers, solitary, few, or clustered in the axils, 

 with a pair of leafy bracts (whence the name, from Siirrepos, two-winged, and 

 axavBos, the Acanthus). 



1. D. Cilidsus, Nees. Hirsute with soft whitish hairs (1° -3° high); 

 leaves nearly sessile, oval or ovate-oblong (14'-2' long) ; flowers 1-3 and almost 

 sessile in the axils; tube of the corolla (V - 1^' long) fully twice the leruph of the 

 setaceous calyx-lobes; the throat short. (Ruellia cillosa, Parsh. R. h3^bridus, 

 Pursh., is only a Southern variety of this.) — Dry soil, Michigan to Illinois, and 

 south wai'd . June - Sept. 



2. D. Strepcns, Nees. Glabrous or sparingly pubescent (l°-4°high); 

 leaves narrowed at the base into a petiole, ovate, obovate, or mostly oblong (2 J' - 5' 

 long); tube of the corolla (about 1' long) little longer than the dilated portion, 

 slightly exceeding the lanceolate or linear calyx-lobes. — Flowers 1 - 5 in each axil, 

 rarely on a slender peduncle, usually almost sessile ; sometimes many and closely 

 crowded, and mostly fruiting in the bud, the corolla small and not expanding 

 (when it is D. raicrinthus, Engelm. ^ Gr.). — Rich soil, Pennsylvania to Wis- 

 consin, and southward. July - Sept. 



Dici.frTERA brachiXta, Spreng. (Justicia brachiata, Pursh), probably 

 gro-vs in the southern part of Virginia. 



