158 ANACARDAICEAE. 



two, sac-like, or none; stamen 1; pistil 1; styles 2, filiform; 

 ovary 4-celled; ovule 1 in each cell; fruit nutlike, compressed, 

 4-lobed, 4-celled, more or less winged or keeled; endosperm oily. 



220. CALLITRICHE. WATE'R STARWORT. 



Low slender usually tufted herbs ; leaves spatulate or linear or 

 both, entire; flowers monoecious, solitary or 2 or 3 in the axil of 

 a leaf, with or without a pair of membranaceous bracts; stami- 

 nate flower a single stamen; pistillate flower a single 4-celled 

 ovary, sessile or pedicelled, with 2 distinct sessile stigmas. 



Callitriche verna L. Aquatic or growing in the mud ; floating leaves obovate, 

 obtuse or emarginate, the others linear or spatulate, 1-nerved, 1-2 cm. long; 

 when terrestrial, leaves all linear; bracts 2, as long as or longer than the fruit 

 or wanting; fruit oval, emarginate, 1 mm. long, the edges grooved and narrowly 

 winged; styles erect, shorter than the fruit. Not rare, in ponds and pools. 



Family 51. ANACARDIACEAE. CASHEW FAMILY. 



Trees or shrubs with resinous or milky acrid juice; leaves 

 alternate, usually compound, without stipules, not punctate; 

 flowers regular, small, polygamo-dioecious or perfect; calyx 5- 

 lobed ; petals 5 ; stamens as many or twice as many as the petals, 

 rarely fewer or more; styles 3; ovary 1-celled, 1-ovuled; fruit 

 generally a small drupe; endosperm scant or none. 



221. RHUS. 



Trees or shrubs, some poisonous to the skin; flowers polyga- 

 mous or dioecious, seldom truly perfect, small, greenish or rarely 

 yellow or rose-color; calyx small, 5-parted; petals 5; stamens 5; 

 ovule basal. 



Leaflets 9-31; fruit red, pubescent. R. glabra. 



Leaflets 3; fruit white, glabrous. R. toxicodendron. 



Rhus glabra occidentalis Torr. Sumac. .Shrub or small tree, 2-5 m. high, 

 with ridged bark, glabrous and somewhat glaucous except the inflorescence; 

 leaflets 9-31, broadly lanceolate, acuminate, serrate, paler beneath, 5-8 cm. 

 long; inflorescence a dense panicle, usually puberulent, 10-12 cm. long; 

 flowers green or yellowish, polygamous; drupes red, 4-5 mm. in diameter, 

 densely clustered, covered with short hairs. Common in the warmer valleys. 



Rhus toxicodendron L. Poison Ivy. Low shrubs, weak or decumbent, 

 50-100 cm. high; leaflets 3, broadly ovate, acuminate, entire, or with a few 

 tooth-like lobes, glabrous or pubescent beneath, 5-10 cm. long, the lateral 

 ones with shorter stalks; petioles longer than the leaflets; panicles shorter 

 than the petioles; flowers green; drupes globose, 4-6 mm. in diameter, shiny, 

 whitish, longitudinally ribbed; stone stria te. In the warmer valleys; very 

 poisonous. Our form seldom or never climbs and has been considered a distinct 

 species, R. rydbergii Small. 



