FLOWERING PLANTS AND FERNS OF ARIZONA 231 



2. PARIETARIA. Pellitory 



Plants annual; leaves alternate, without stipules, the blades lanceo- 

 late to ovate; inflorescences small, glomerate, subtended by leafy 

 bracts; style short, the stigma tufted; achene enclosed by the per- 

 sistent calyx. 



In Arizona these insignificant plants are in flower almost throughout 

 the year. 



Key to the species 



1. Involucre 2 to 3 times as long as the flowers; stems simple or sparingly branched, 

 erect or ascending; leaf blades commonly lanceolate or ovate-lanceolate. 



1. P. PENNSYLVANICA. 



1. Involucre commonly less than twice as long as the flowers; stems diffusely 

 branched from the base; leaf blades commonly broadly ovate or suborbi- 

 cular, sometimes oblong or lanceolate 2. P. florid ana. 



1. Parietaria pennsylvanica Muhl. ex. Willd., Sp. PL 4: 955. 1806. 

 Grand Can von (Coconino County), and Yavapai, Maricopa, Pinal, 



and Pima Counties, 1,300 to 4,000 (?) feet. Throughout most of 

 temperate North America. 



2. Parietaria floridana Nutt., Gen. PL 2: 208. 1818. 



Parietaria debilis of American authors. Not Forst. 



Throughout much of the State, 4,000 feet or lower. Southeastern 

 United States to southern California. 



Parietaria obtusa Rydb. apparently is only a form with obtuse bracts 

 and sepals. 



29. LORANTHACEAE. Mistletoe family 



Plants parasitic on trees and shrubs, with or without chlorophyll; 

 stems jointed, brittle when dry; leaves opposite; flowers dioecious; 

 perianth calyxlike, small, with 2 to 4 lobes or teeth; stamens inserted 

 on the perianth, the anthers sessile; ovary inferior, 1-celled; fruit a 

 1 -seeded berry. 



The plants of both genera sap the vitality of the host tree and, when 

 abundant, cause considerable damage in forests. Birds are very 

 fond of the berries of Phoradendron and through their agency the 

 viscid seeds are transferred from tree to tree. The Papago Indians 

 dry the berries of P. californicum in the sun and store them as food 

 supply. The Hopi are reported to use P. juniperinum medicinally. 

 The berries of some species are reputedly poisonous and contain a 

 principle similar in action to epinephrin. The European mistletoe 

 (Viscum album) and some of the American species of Phoradendron 

 are popular for Christmas decoration, because of their white or whitish 

 pearl-like berries. 



Key to the genera 



1. Fruits sessile, globose or nearly so, whitish or reddish; flowers in axillary spikes: 

 pistillate calyx normally 3-toothed; anthers 2-celled_ 1. Phouadexdrox. 



1. Fruits on short, often curved pedicels, longer than wide, greenish, bluish or 

 purplish; flowers not in spikes; pistillate calyx normally 2-toothed; anthers 

 1-celled 2. Arceuthobium. 



