G.12) CLASSIFICATION AND DESCRIPTION 73 
thinner and rather pubescent beneath. Fruit globose, } in. broad, 
on a bract usually quite rounded at base. 
This is usually considered as a variety of the last-named species. 
It is found from New York south and west. 
3. Tilia heterophylla, Vent. (WHITE 
Basswoop.) Leaves large, often 8 in. 
broad, smooth and bright green above, 
silvery white and downy beneath, with 
darker, purplish veins. A large tree; 
wild in Pennsylvania, west and south, and 
often cultivated. 
T. heterophylla, 
4. Tilia Europga, Mill. (European LINDEN.) 
Leaves twice as long as the petioles, and smooth ex- 
cept a woolly tuft in the axils of the veins beneath. 
Small and large leaved varieties are in cultivation. 
The flowers have no petal-like scales among the 
+ stamens, while the American species have. An orna- 
T. Europa. mental tree with dense foliage; often cultivated from 
Europe. The twigs are more numerous and more slender than 
those of the American species. Nearly a score of named varieties 
are in cultivation. Var. laciniata has deeply cut and twisted leaves. 
OrpER IX. RUTACEAS. (Rut Famtty.) 
Shrubs and trees, rarely herbs, in most cases with 
transparent-dotted, heavy-scented foliage. A rather 
large order in warm climates. 
Genus 12. XANTHOXYLUM. 
Shrubs or trees with mostly odd- 
pinnate, alternate leaves. The stem 
and often the leaflets prickly; flow- 
ers small, greenish or whitish ; fruit 
dry, thick pods, with 1 to 2 seeds. 
1, Xanthéxylum Americanum, Mill. 
(NORTHERN PRICKLY-ASH. TOOTHACHE- 
Tree.) Leaves and flowers in sessile, ‘ 
axillary, umbellate clusters; leaflets 5 to " X, Americdnum, 
