Herbs often hispid with stinging hairs, with leaves opposite or alternate and no stipules. Flowers axillary, solitary. Calyx adherent to the ovary, 4 or 5-parted, lobes persistent, equal. Petals 5 or 10, in 2 circles, often cucullate, inserted on the calyx. Stamens indefinite, inserted with the petals, free or cohering in several sets. Ocary 1-celled, with several parietal placentae, or one central Style 1. Ovules pendulous. Embryo in the axis of fleshy albumen.

Genera 18, species 70, natives of America.

MENTZE'LIA, L. (In honor of C. Mentzel, physician to the Elector of Brandenburg.) Calyx tubular, limb 5-parted; petals 5 to 10, flat, spreading; stamens ∞, 30 to 200; ovary inferior; styles 3, filiform, connate, and often spirally twisted; stigmas simple, minute; capsule 1-celled, many-seeded. - Branching herbs. Lvs. alternate.

1 M. oligosperma Nutt. Very rough, with barbed hairs; st. dichotomous; lvs. ovate-lanceolate, tapering to very short petioles, lobed or incisely dentate; petals entire, cuspidate, expanding in sunshine; stam. 20 or more, shorter than the petals; caps. 3 to 5-seeded. -Order LIII Loasaceae Loasads 705 Dry or rocky places, Pike Co., Ill. (Mead), and Mo. to Tex. Rt. tuberous. St. 1f high, divaricately branched. Lvs. 10 to 15" by 6 to 8", upper ones ovate. Fls. solitary, of a deep, golden yellow, 8 to 10" diam., very fugacious. Caps. cylindrie, very small. May - Jl.

2 M. Lindleyi Torr. & Gr. Golden Bartonia. Hispid; lvs. ovate-lanceolate, pinnatifid, lobes often dentate; fls. solitary or nearly so, terminal; petals broadly obovate, very abruptly acuminate; filaments filiform, and with the seeds numerous. -Order LIII Loasaceae Loasads 706 Gardens. St. decumbent, branching, 1 to 3f in length, with golden yellow fls. 2 to 3' diam., the beauty of which is greatly heightened by innumerable, thread-like, yellow stamens. (Bartonia aurea Lindl.) † California.