Handbook of Thkes op the 1N"oethet:.n States and Canada. 451 



Leaves alternate, petiolate, conduplicate in the biul. Fkm-crs small, greenish, polygamo- 

 dioecious, in capitate clusters (or the fertile ones sometimes solitary) with slender peduncles, 

 from the axils of the lower leaves or of caducous bracts, the sta'rainate flowers numerous : 

 calyx minutely 5-lobed ; petals Ti, minute and thick or none ; stamens .5-15 in the staminate 

 flowers, exserted and inserted with the petals on the edge of the entire or lobed disk ; pistillate 

 flowers sessile at the end of the peduncle, few together, bracted ; stamens included : ovary 

 1-2-celled and style elongated, slender, curved and stigmatic towards the apex on one side. 

 Fruit an oblong or ovoid drupe with thin tart juicy flesh and thick-walled horny compressed 

 ridged or winged stone ; embryo straight. 



Xussa is the name of a water nymph and applied to the genus because of its species 

 growing in wet places. 



KEY TO TUB SPECIES. 



a Leaves entire ; fruit less than % iu. long 



Stone little flattened and indistinctly ribbed N. sylvatica. 



Stone distinctly flattened and prominently ribbed N. biflora. 



a' Leaves remotely dentate : fruit 1 in. or more long ; stone with acute ridges. N. aquatica. 



For species see pp. 362-367. 

 Division 3. GAMOPETAIi.a:. 

 Plants with petals more or less united, or sometimes separate or wanting. 



HEATH FAMILY. ERICACEAE DC. 



A large and interesting family of trees and shrubs of world-wide distribution in tropical 

 and temperate regions. A few over a thousand species are known, grouped in about sixty 

 genera. Of these twenty-one genera are found within the United States, seven having arbor- 

 escent representatives. 



Leaves alternate, simple, and without stipules. Flowers regular, perfect: calyx free from 

 the pistil, 4-r)-lobed : corolla regular, hypogenous, 5-lobed or parted (exceptionally 4-Iobed or 

 somewhat 2-lipped) imbricated; stamens as many or twice as many as the lobes of the corolla 

 and mostly free ; anthers introrse, 2-celled, each cell opening by a terminal pore commonly 

 prolonged and bearing an appendage: ovary superior (inferior in Vaeeinium), 4-10-celIed, with 

 numerous anatropous ovules : style simple, columnar and with capitate stigma. Fruit a cap- 

 sule, drupe or berry : seeds with small embryo and albumen. 



KEY TO THE GENERA. 



a Fruit a septicidally dehiscent capsule : leaves persistent ; flowers in 



Terminal clusters: corolla bell-shaped, .5-cleft : leaves revolute Rhododendron. 



Axillary clusters ; corolla .5-Iobed saucer-shaped and containing pouches : leaves flat. 



Kalmia. 

 a' Fruit a loculicidally dehiscent capsule ; flowers in terminal panicles ; leaves deciduous. 



Oxydendrum. 

 a° Fruit a berry ; anther-cells prolonged : corolla campanulate or urceolate, white ; leaves 

 deciduous Vaeeinium. 



THE RHODODENDRONS. Genus RHODODENDRON L. 



Small trees and shrubs with bitter astringent properties and showy flowers, of some over 

 one hundred and fifty species of eastern and southern Asia and the adjacent islands and North 

 America. They are largely grown for ornamental purposes and many garden varieties have 

 been produced by hybridization and selection. Of the eight species found in the United States 

 one is arborescent on the Atlantic coast region and another rarely on the Pacific slope. 



Leaves clustered at the ends of the branchlets. persistent and coriaceous with revolute 

 entire margins : midribs broad, petioles stout. Flowers in terminal corymbs or umbels from 

 terminal scaly cone-like buds: calyx 5-lobed or parted, persistent; corolla campanulate with 

 5 nearly regular lobes; disk fleshy, lobed; stamens usually 10 and somewhat unequal, declined 

 and spreading ; filaments pilose at base and attached to the backs of the anthers : ovary 5-celled 

 with slender exserted persistent style and many anatropous ovules in each cell attached to 

 the axile placenta. Fruit a woody capsule, 5-20-valved, septicidally dehiscent from the 

 summit and containing many seeds with coat laciniated at the ends. 



The name is from Greek words meaning Rose-tree. 



For species see pp. 368-369. 



THE LAURELS. Genus KAL]\HA L. 



Small trees and shrubs of 6 or 7 species, all of which are found in the United States 

 excepting one, which is a native of Cuba. The following one species is the only arborescent 

 representative. 



