Genus 17. 



SPURGE FAMILY, 



3. Poinsettia heterophylla (L.) Kl. & 



Garcke. Various-leaved Spurge. 



Fig. 2768. 



Euphorbia heterophylla L. Sp. PI. 453. 1753. 

 F. heterophylla Kl. & Garcke, Monatsb. Akad. 



Berlin 1859: 253. 



Annual or biennial, bright green, pubescent 

 or nearly glabrous. Stem mostly erect, I-3 

 tall, woody below, with the branches ascend- 

 ing, or the lower spreading, leafy at the ends ; 

 leaves alternate, very variable, linear to orbicu- 

 lar, entire, undulate, sinuate or dentate, the 

 uppermost often liddle-shaped and blotched 

 with red ; all slender-petioled ; involucres clus- 

 tered at the ends of branches, il" long, about 

 equalling the peduncles; cleft into 5 ovate or 

 oblong laciniate lobes, the sinuses bearing i 

 or several sessile glands without appendages ; 

 capsule glabrous or minutely pubescent, 3" in 

 diameter; seeds oblong-ovoid, li" long, trans- 

 versely wrinkled and tuberculate. 



Illinois to South Dakota, Florida, Kansas and 

 Texas. Tropical America. April-Nov. 



Family 71. CALLITRICHACEAE Lindl. Nat. Syst. Ed. 2, 191. 1836.* 



Water St.\rwort Family. 

 Herbaceous aquatic or rarely terrestrial plants, with slender or capillary stems, 

 opposite exstipulate entire spatulateor linear leaves, and minute perfect or monoe- 

 cious axillary flowers. Perianth none. Bracts 2, sac-like or none. Stamen i ; 

 filament elongated, filiform ; anthers cordate, 2-celled, opening by lateral slits. 

 Pistil I ; ovary 4-celled; ovules i in each cavity; styles 2, filiform, papillose nearly 

 the whole length. Fruit compressed, lobed, the lobes more or less winged or 

 keeled on the margins, separating at maturity into 4 flatfish i-seeded carpels. 

 Seed anatropous, pendulous; endosperm fleshy; embryo straight or slightly curved, 

 nearly as long as the endosperm. 



Consists of the following genus : 



I. CALLITRICHE L. Sp.Pl. 969. 1753. 



Characters of the family. The affinities are variously regarded by botanical authors, 

 some placing it in Haloragid.^ceae, some in Onagraceae, others near Euphorbiaceae, the posi- 

 tion here maintained. [Greek, beautiful hair, from the hair-like stems.] 



About 20 species, of very wide geographic distribution. Besides the following, about 7 others 

 occur in the southern and western parts of North America. Type species ; Callitriche paltistris L, 

 Pruit short-peduncled : Ijracts wanting; terrestrial. i. CAttstiiii. 



Fruit sessile : aquatic, or some forms growing in mud. 

 Bracts present. 



Fruit oval, flat on the face, longer than the styles. 2. C. pahistri^. 



Fruit obovate, plano-convex, shorter than the styles. 3. C. heterophylla. 



Bracts none; leaves all linear, submersed. 4. C. antnmna'lis. 



I. Callitriche Austin! Engelm. Terrestrial Water-Starwort. Fig. 2769. 



Callitriche terrestre Raf. Med. Rep. (II.) 5: 358. 1808? 

 Callitriche dcflexa var. Austini Hegelm. Ver. Bot. Ver. Brand. 



9: 15. 1867. 

 C. Austini Engelm. in A. Gray, Man. Ed. 5, 428. 1867. 



Tufted, the branches spreading on the ground or ascend- 

 ing, -2' long. Leaves spatulate or obovate, 3-nerved, 

 i*"-2" long, about i" wide, obtuse, tapering at the base 

 into a short margined petiole, destitute of stellate scales; 

 fruit about i" long and nearly i" broad, deeply notched 

 at both ends, its lobes with a narrow marginal wing or 

 raised border, with a deep groove between them; peduncle 

 shorter than or slightly exceeding the fruit; styles per- 

 sistent, not longer than the fruit, spreading or reflexed. 



In damp, shaded places, Connecticut to Delaware, Ohio, Mis- 

 souri, Louisiana, Texas and Mexico. July-Sept. The dried 

 plant exhales a pleasant odor like melilot, 



* Text written for the first edition by the late Rev. Thomas Morong, here slightly revised. 



