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 diffuse 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 (haustoria) ; 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. 



