CUPUL1FERJS. (OAK FAMILY.) 331 



1. L. Canadensis, Gaudichaud. Leaves ovate, pointed, strongly feather- 

 veined, long-petioled ; stipule single, 2-cleft. Throughout the Atlantic 

 States, and coming within our borders at the northwest. 



5. PARIETARIA, Tourn. PELLITORY. 



The staminate, pistillate, and perfect flowers intermixed in the same invo- 

 lucrate-bracted cymose axillary clusters. Diffuse or tufted herbs, with entire 

 3-ribbed leaves and no stipules. 



1. P. Pennsylvanica, Muhl. Low, simple or sparingly branched, 

 minutely downy : leaves oblong-lanceolate, thin, veiny, roughish with opaque 

 dots : flowers shorter than the leaves of the involucre. From Colorado to 

 Nevada and eastward across the continent. 



6. HUMULUS, L. HOP. 



Sterile flowers with 5 sepals and 5 erect stamens. Fertile flowers in short 

 spikes with leafy imbricated bracts, each 2-flowered. Akene invested with the 

 enlarged scale-like calyx. Twining rough perennials, with stems almost 

 prickly downwards, mostly opposite heart-shaped and palmately 3 to 7-lobed 

 leaves. 



1. H. Lupulus, L. Leaves commonly longer than the petioles: the 

 fruiting calyx, akeiie, etc., sprinkled with yellow resinous grains, giving the 

 bitterness and aroma of the hop. In the mountains from New Mexico to 

 British America and eastward across the continent. 



ORDER 74. CUPULIFERJE. (OAK FAMILY.) 



Trees or shrubs, with alternate and simple straight- veined leaves, 

 deciduous stipules, and monoecious flowers, both kinds of flowers in 

 catkins, or the fertile solitary, clustered, or spiked, the 1 -celled, 1 -seeded 

 nut with, or without an involucre. 



Tribe I. Both kinds of flowers in scaly catkins, 2 or 3 under each bract, and no involucre 



to the naked often winged small nut. BETULE.E. 



1 Bet ul a. Stamens 2, with bifurcate filaments and separate anther-cells. Bracts 3-lobed, 

 becoming coriaceous and caducous. Nutlet broadly winged. 



2. Alnus. Stamens 4 : anther-cells contiguous. Bracts entire, becoming woody, per- 



sistent. Nutlet not winged. 



Tribe II. Sterile flowers destitute of a true calyx, consisting of several stamens included 

 under and more or less adnate to a bract : filaments short ; anthers 1-celled. Fertile 

 flowers in a scaly bud or catkin, two under each fertile bract, each with one or more 

 bractlets, which form a foliaceous involucre to the nut. COBYLE^. 



3. Corylus. Bract of staminate flower furnished with a pair of bractlets inside. Invo- 



lucre leafy-coriaceous, enclosing the large bony nut. 



Tribe III. Sterile flowers with a distinct 4 to 7-lobed calyx, including 3 to 20 stamens : 

 filaments exserted ; anthers 2-celled. Fertile flowers one or few enclosed in a cupule 

 consisting of bracts variously consolidated. QUERCINE^E. 



4. Quercus. Sterile flowers in slender catkins. Cupule 1-flowered, scaly and entire; 



nut hard and terete. 



