582 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



76. HYPERICACEAE. St. Johnswort family 

 1. HYPERICUM. St. Johnswort 



The Arizona species perennial, glabrous herbs; leaves opposite, 

 simple, sessile, entire, glandular-punctate; flowers perfect, regular, the 

 sepals and petals 4 or 5, the petals yellow or salmon color; stamens 

 numerous, usually in 3 to 5 clusters with the filaments united below; 

 ovary 3-celled or with 3 placentas; capsule dehiscent, many-seeded. 



The common St. Johnswort (H. perforatum L.), a European plant 

 extensively naturalized in the United States, contains a photosensi- 

 tizing jjrinciple that causes blistering and loss of hair in white-skinned 

 horses, cattle, and sheep if exposed to strong sunlight after eating the 

 plant. It is not known whether the native species have this effect. 



Key to the species 



1. Stems erect from creeping rootstocks, 20 to 70 cm. long; leaf blades 10 to 35 

 mm. long, black-dotted along the margin; flowers several or numerous, 

 in leafy terminal panicles; petals yellow, 7 to 14 mm. long. 



1. H. FORMOSUM. 



1. Stems procumbent, often forming mats, rooting at the lower nodes, 3 to 25 cm. 

 long; leaf blades 4 to 12 mm. long, not black-dotted; flowers few in terminal 

 cymes, sometimes solitary, occasionally axillary; petals salmon-colored, 

 2 to 4 mm. long 2. H. anagalloides. 



1. Hypericum formosum H. B. K., Nov. Gen. et Sp. 5: 196. 1821. 

 Apache County to Coconino County, south to Cochise and Pima 



Counties, 7,000 to 9,000 feet, mctist soil in coniferous forests, July to 

 September. Wyoming to Arizona, southern California, and Mexico. 



2. Hypericum anagalloides Cham, and Schlecht., Linnaea 3: 127. 



1828. 

 Kaibab Plateau, Coconino County (Grand Canyon Herb. 956). 

 Montana to British Columbia, northern Arizona, and southern 

 California. 



77. ELATINACEAE. Waterwort family 



1. ELATINE.S5 Waterwort 



Plants herbaceous, annual, semiaquatic, glabrous; stems slender, 

 rooting at the nodes, seldom more than 5 cm. long; leaves opposite, 

 simple, entire; flowers axillary, minute, commonly 2-merous; fruit a 

 dehiscent capsule, with several to many seeds. 



1. Elatine triandra Schkuhr, Bot. Handb. 1: 345. 1791. 



Grows in Arizona on the muddy margins of ponds, 5,000 feet or 

 higher. Widely distributed in the Northern Hemisphere. 



There occur in Arizona both the typical form of the species (var. 

 genuina Fassett), with leaves linear to spatulate, often emarginate, 

 and seeds with more than 15 transverse rows of pits; and var. brachy- 

 sperma (A. Gray) Fassett (E. brachysperma A. Gray), with leaves 

 linear or narrowly oblong, seeds with not more than 15 rows of pits. 

 The typical form has been collected on the San Francisco Peaks 

 (MacDougal 273), in southern Coconino County (Peebles 14410), and 

 in the Pinaleno Mountains, Graham County (Shreve 5219). The var. 



w Reference: Fassett, Norman C. elatine and other aquatics. Rhodora 41: 367-376. 1939. 



