Genus 17. 



SPURGE FAMILY, 



3. Poinsettia heterophylla (L.) Kl. & 



Garcke. Various-leaved Spurge. 



Fig. 2768. 



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

 P. 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 fiddle-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, iV 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 Starwort Family. 

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

 opposite exstipulate entire spatulate or 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-ceIled, 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 flattish i-seeded carpels. 

 Seed anatropous, pendulous; endosperm fleshy; embryostraightor slightly curved, 

 nearly as long as the endosperm. 



Consists of the following genus : 



I. CALLITRICHE L. Sp. PI. 969. 1753. 



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

 some placing it in Haloragidaceae, some in Onagraceae, others near Euphorwaceae, 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 palustris L. 

 Fruit short-peduncled ; bracts wanting; terrestrial. i. C. Austin!. 



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

 Bracts present. 



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



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



Bracts none ; leaves all linear, submersed. 4. C. autumnalis. 



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



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

 Callitriche deflexa 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, V-2' long. Leaves spatulate or obovate, 3-nerved, 

 1 4 -2" long, about l" 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. 



