526 LOASACEAE 



LOASACEAE. Loasa Family 



Herbs or bushes with oitlior rdutili or stinfjinp: hairs, and often with white de- 

 ciduous bark. Leaves in ours alternate. Flowers rej^ular, complete, white, yellow 

 or reddish. Calj-x-limb 5-lobed. Petals 5 (rarely 8 or 10). Stamens usually very 

 numerous, sometimes few and definite, inserted with the petals on the base of the 

 calyx-tube. Ovary inferior, 1-celled; style 1, entire or cleft. Fruit a capsule, 

 crowned with the calyx-lobes. — Genera 13, species 250, South and North America 

 (especially Chile to California), and 1 monotypic genus in South Africa and 

 Arabia. 



Bibliog. — Urban, I., and Gilg, E., Monographia Loasacearum (Nova Acta Acad. Nat. Cur. 

 76':l-38-i, t. 1-8, — 1900). Rydberg, P. A., Some generic segregations: Bicuspidaria, Touterea, 

 Acrolasia (Bull. Torr. Club 30:275-278, — 1903). Heller, A. A., Botanical Exploration in Cali- 

 fornia: Loasaceae (Muhl. 2:98-100,-1905). Greene, E. L., The genus Nuttallia (Lflts. 1:209- 

 210, — 1906). Davidson, A., A revision of the western INIentzelias (Bull. S. Cal. Acad. 5:13-18, — 

 1906). Macbride, J. F., A revision of Mentzelia, sect. Trachyphytum (Contrib. Gray Herb. 

 56:24-28,-1918). 



Stamens many; seeds few to many. 



Stamens inserted below petals; seeds on 3 parietal placentae; style entire or 3-cleft 



1 T^IeNTZEIjIA 



■ Stamens inserted on the petals; seeds on 5 parietal placentae. 



Corolla with petals united only at base, the stamens adnata to the united bases; style 



5-cleft 2. EucNiDE. 



Corolla sympetalous, the stamens borne on the tube; style entire 3. Sympetaleia. 



Stamens 5; style entire; seed solitary 4. Petalonyx. 



1. MENTZELIA L. 



Erect or diffuse herbs. Leaves in age brittle, adhering very tightly to clothing 

 by means of barbed hairs. Flowers terminal, solitary or cymose, small or showy. 

 Capsule dehiscent at the summit, few to many-seeded. Placentae 3, seldom 5 or 6. 

 Seeds prismatic, irregularly angled or flat ; endosperm scanty. — Species about 55, 

 North and South America, mostly tropical and subtropical. (C. Mentzel, a German 

 botanist of the 17th century.) 



In Mentzelia in general corolla size is variable. The characters of the mature seed are here 

 regarded as the most dependable. The style is more or less 3-cleft, save that in M. micrantha it is 

 entire. The petals are about 8 in M. reflexa. In the series Mentzelia dispersa-affinis and in the 

 gracilenta-albicaulis series the species seem to overlap and are difficult of discrimination. 



A. Seeds flattish, hroadly wing -margined; stamens numerous, the 5 to 10 outer filaments petaloid. 



Biennials. 



Petals broadly oblanceolate, 1% to 21^ inches long; 5 outer filaments petaloid but fertile; 



cismontane and transmontane 1. M. laevicaulis. 



Petals narrowly obovate, 4 to 8 lines long ; transmontane. 



Calyx-lobes eventually deciduous, the short calyx-tube persistent as a narrow cup on 



the capsule 2. M. viulti flora. 



Calyx -lobes persistent, divided almost down to the capsule (calyx-tube essentially none).. 



3. M. leucophylla. 



Perennial ; calyx with a short tube at base, the entire calyx persistent on the capsule ; Mono Co 



_ „ , 4.M. torreyi. 



B. Seeds not oroadly wing-margined ; annuals. 



Seeds rugulose with rounded angles and 2 to 4 deep folds ; transmontane deserts. 



Outer filaments dilated above and prolonged on either side of the anther as a shoulder or 

 tooth. 

 Flowers subtended and the ovary concealed by a pair of Avhite scarious bracts with green 

 laciniate margin; prolongation of filament equaling or exceeding the anther; 



capsules erect 5. M. involuerata. 



Flowers subtended by small f oliaceous bracts not concealing the ovary ; prolongation of 

 filament not equaling the anther. 



Capsules linear, erect, 10 to 12 lines long 6. M. peirsonii. 



Capsules oblong, deflexed in age, 4 to 5 lines long 7. M. tricuspis. 



Filaments filiform or somewhat dilated but not produced on either side of the anther ; cap- 

 sules reflexed 8. M. reflexa. 



Seeds minutely tuberculate or appearing smooth ; outer filaments petaloid or filiform but not pro- 

 duced on either side of anther (except in no. 9). 



