260 CONTRIBUTIOlSrS FROM THE NATIO:^rAL HERBARIUM. 



1. Symphoricarpos albus (L.) Blake. Snowberry. 

 Sparsely escaped from cultivation; Georgetown; Woodley Park. May-July; fr. 



July-late winter. Northern U. S. (S. racemosus Michx.) 

 Our plants are var. laevigatus (Fernald) Blake. 



2. Symphoricarpos orbiculatus Moench. Corai.berry. 

 Abundantly escaped from cultivation; old fields, roadsides, and edges of woods. 



July-Aug.; fr. Aug.-spring. Northern and western U. S. (S. vulgaris Michx.; 5. 

 symphoricarpos MacM.) 



3. TRIOSTEUM L. Horse gentian. 



Leaves united by their bases around the stem. Corolla purplish brown. 



1. T. perfoliatum. 

 Leaves distinct. 



Leaves more or less auricled and clasping at the base; flowers dull red. 



2. T. aurantiacum. 



Leaves narrowed to the merely sessile base; flowers yellowish. .3. T. angustifolium. 



1. Triosteum perfoliatum L. 



Sparingly distributed in open woods. May-June; fr. July-fall. Eastern U. S. 



2. Triosteum aurantiacum Bicknell. 



Corcoran woods and Reno. May; fr. Oct. Northeastern U. S. 

 .3. Triosteum angustifolium L. 



Occasional in damp woods. May-June; fr. July. Eastern U. S. 



4. VIBURNUM L. 



The snowball, V. opulus sterile DC, is commonly cultivated. The highbush cran- 

 berry, F. opulus americanum Ait., and the wayfaring tree, V. lantana L., are also 

 cultivated. The latter, a native of Europe, has ovate leaves; the former, native in 

 the northern states, has 3-lobed leaves, like the snowball. 



Leaves mostly 3-lobed, soft-downy beneath 1, V. acerifolium. 



Leaves not 3-lobed. 



Leaves with prominent teeth and veins. 



Stipules long, linear; leaves usually very ehort-petioled 2. V. affine. 



Stipules very small or wanting; leaves usually long-petioled. 



Petioles usually glabrous beneath, if hairy the hairs not chiefly clustered; 



hairs on lower surface of leaves mostly confined to axils of veins, often 



cobwebby, but not chiefly clustered 3. V. dentatum. 



Petioles usually densely and lower leaf surface usually more generally hairy, 



the pubescence chiefly of clustered hairs. 



Leaves of an ovate type, longer than broad, with about 5 pairs of veins. 



4. V. scabrellum. 



Leaves often orbicular, about as broad as long, the veins more prominent on 



the average and more numerous, 7-11 pairs to the leaf. 



6. V. pubescens. 

 Leaves finely toothed or entire, with inconspicuous veins. 



Flower and fruit clusters long-stalked. 



Peduncles shorter than the cymes; leaves thin, usually irregularly crenate. 



6. V. cassinoides. 



Peduncles usually equal to or longer than the cymes; leaves thick, usually 



entire 7. V. nudum. 



Flower and fruit clusters nearly sessile. Leaves oval, finely and sharply serrate. 



8. V. prunifolium. 



1. Viburnum acerifolium L. Arrow-wood. 



Common in woods. May-June.; fr. Aug. -winter. Eastern N. Amer. 



