LORANTHACEAE. 79 



dioecious or monoecious; staminate flowers with a deeply 4- 

 parted calyx and 4 stamens; pistillate flowers with 4 sepals, the 

 two inner larger and in fruit enclosing the akene; the two outer 

 smaller and spreading. 



Leaves soft-pubescent on both sides. U. holosericea. 



Leaves quite glabrous above, somewhat pubescent beneath. U. lyallii. 



Urtica holosericea Nutt. Tall, 2-3 m. high, usually somewhat bristly, 

 densely soft-pubescent throughout; leaves ovate-lanceolate, acuminate, sub- 

 cordate, coarsely and evenly dentate, soft-pubescent on both sides, 8-16 cm. 

 long; petioles short; staminate flowers in loose narrow panicles shorter than 

 the leaves; pistillate panicles denser, in the axils of the uppermost leaves. 

 Variable; common in moist places especially in the warmer valleys. 



Urtica lyallii Wats. Very much like U. holosericea, but not so tall, 1-2 m. 

 high; stem merely bristly or glabrous; leaves broadly ovate, cordate, very 

 coarsely dentate, green and usually glabrous above, pubescent or glabrous 

 beneath. Infrequent, in moist places. 



109. PARIETARIA. 



Annual or perennial difi^use or erect herbs without stinging 

 hairs; leaves alternate, entire, 3-nerved, petioled, without 

 stipules; flowers axillary, in compact clusters, polygamous, sub- 

 tended by an involucre of leafy bracts; calyx of the staminate 

 flowers deeply 4-parted, that of the fertile flowers tubular or 

 campanulate, 4-lobed, surrounding the ovary and the akene. 



Leaves rounded or cuneate at base; bracts equalling the 



flowers. P. debilis. 



Leaves attenuate-acute at base ; bracts exceeding the flowers. P. pennsylvanica. 



Parietaria debilis Forst. Stems slender, pubescent, simple or branched 

 at base, weak, 8-20 cm. long; leaves ovate, obtuse, rounded or cuneate at 

 base, 4-12 mm. long, rough-hairy above; petioles short; flowers few in each 

 cluster; bracts oblong-linear, 1-2 mm. long, scarcely longer than the flowers; 

 akenes shining gray, 1 mm. long. Crevices of basaltic cliffs near Lewiston. 



Parietaria pennsylvanica Muhl. Very similar to P. debilis; leaves lan- 

 ceolate, attenuate-acute at base, 2-6 cm. long; bracts much exceeding the 

 flowers, 3-5 mm. long. Basalt crevices along the Snake and Clearwater 

 Rivers. 



Family 28. LORANTHACEAE. Mistletoe Family. 



Parasitic shrubs or herbs, yellow or yellowish-green, growing 

 on woody plants and absorbing food from their sap through 

 specialized roots (Jiaustoria) ; leaves opposite ; flowers regular, 

 terminal or axillary, clustered or solitary, dioecious (in ours); 

 calyx-tube adnate to the ovary; stamens 2-6; ovary solitary, 

 erect; style simple or none; stigma terminal; fruit a berry; 

 seed solitary; endosperm usually copious and fleshy. 



