Herbs mostly perennial, with entire or rarely dentate leaves, and small or large very irregular flowers, variously clustered or solitary in the axils. Calyx deeply 4-5-parted, the segments narrow. Corolla-tube slender, short or elongated, curved or nearly straight, the limb conspicuously 2-lipped; upper lip interior in the bud, erect or ascending, concave, entire, or 2-dentate; lower lip spreading, 3-cleft. Stamens 2, inserted on the throat of the corolla, not exceeding the upper lip; anther-sacs ovate or oblong, slightly divergent, not mucronate, separated by a rathed broad connective. Ovules 2 in each cavity of the ovary; style slender; stigma entire, or 2-lobed. Capsule contracted at the base into a long stipe, about 4-seeded. Seeds flat, orbicular or ovate, the placentae not separating from the walls of the capsule. [Greek, double anthers.]

About 100 species, natives of tropical America, a few in tropical Asia and Africa. Besides the following, 4 others occur in the southern and southwestern United States. Type species: Dianthera americana L.

Flowers capitate, the heads dense, at length oblong. Flowers in loose spikes.

1. D. americana.

Flowers in pairs in the spikes.

2. D. ovata.

Flowers scattered singly along the spikes.

3. D. lanceolata.

1. Dianthera Americana L. Dense-Flowered Water Willow

Fig. 3893

Dianthera americana L. Sp. Pl. 27. 1753.

Perennial, glabrous; stem erect, grooved and angled, slender, usually simple, 1°-3°. high. or sometimes 6° long when growing in water. Leaves lanceolate or linear-lanceolate, gradually acuminate, 3'-6' long, 3"-8" wide, entire, narrowed at the base into short petioles, or sessile; flowers violet, or nearly white, capi-tate-spicate at the ends of slender axillary peduncles which are shorter than or equal to the leaves; bractlets linear-subulate, shorter than the flowers; corolla 5"-6" long, its tube shorter than the lips, the base of the lower lip rough and palate-like; capsule 6" long, exceeding the calyx, its stipe about the length of the slightly compressed body.

In water and wet places, Quebec to Ontario, Michigan, Georgia and Texas. May-Aug.

1 Dianthera Americana L Dense Flowered Water Willo 5641 Dianthera Americana L Dense Flowered Water Willo 565

2. Dianthera Ovata Walt. Loose-Flowered Water Willow

Fig. 3894

Dianthera ovata Walt. Fl. Car. 63. 1788.

Perennial, glabrous; stem ascending or erect from a horizontal base, slender, 6'-2o' high, simple, or sparingly branched. Leaves short-petioled, or sessile, ovate, oblong or oval, l' - 3' long, 8"-18" wide; flowers opposite in loose slender-peduncled axillary spikes, which become 1'-3' long; peduncles shorter than or but little exceeding the leaves; calyx-segments narrowly linear, much longer than the bracts and bractlets; corolla pale purple, 4"-s" long; capsule about 6" long.

In wet soil, especially along streams, southern Virginia to Florida. Records from Arkansas and Texas apply to the following species. June-Aug.

3. Dianthera Lanceolata (Chapm.) Small. Narrow-Leaved Water Willow

Fig. 3895

D. ovata lanceolata Chapm. Fl. S. States 304. 1860. D. lanceolata Small; Britton, Man. 855. 1901.

Perennial, puberulent; stem erect or spreading, more or less branched, 4'-12' long. Leaves linear to linear-elliptic or elliptic-lanceolate, 1 1/4' - 4' long, more or less acuminate, undulate, sessile or nearly so; flowers in interrupted slender spikes 1 1/4'-4' long; calyx-segments narrowly linear, 2 1/2-3 1/2" long; corolla whitish or pale-purple, about 5" long, the lips nearly as long as the tube, which is saccate near the base, the upper lip truncate or retuse, the lower one 3-lobed, the middle lobe truncate or retuse, the lateral ones obtuse; capsule 7"-8" long, the body as long as the stipe-like base or shorter.

In swamps and low grounds, Missouri to Tennessee, Florida and Texas. June - Sept.

3 Dianthera Lanceolata Chapm Small Narrow Leaved W 566