POLYGONACE.E — EUPHOEBIACE^ 



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walks and in yards, and commonly mistaken for sod: leaves small, mostly 

 oblong, entire: sepals very small, green with a broad white margin: sta- 

 mens 5 or more: stigmas usually 3. Annual. 



P. er6ctum, Linn. Taller knotivecd. One ft. or more high: 



leaves three or four times larger, oblong or oval and obtuse. 



Common annual. 



aa. Smartweeds; flowers in terminal spikes, mostly pinkish. 

 b. Sheaths of leaves (surrounding stem) hairy on the 



edge, or the margin with a spreading border, 

 P. orientals, Linn. Prince's feather. Several feet tall, 

 soft-hairy: flowers in long cylindrical nodding spikes: leaves 

 ovate: stamens 7. India; cultivated. Annual. 



P. Persicaria, Linn. Smartweed. Lady's thumb (from the 

 dark blotch near the center of the leaf). Fig. 455. About 1 ft. : 

 leaves lanceolate: spikes oblong, dense and erect: stamens 

 usually 6: stigmas 2. Weed from Europe. 



P. Hydropiper, Linn. Smartweed. Herbage very pungent 

 or"smarty:" leaves oblong-lanceolate: spikes short and nod- 

 ding, the flowers greenish : stamens 6: stigmas 3. Low 

 455 grounds. Annual. 



Polygonum ^- iiydropiperoides, Michx. Smartweed. Herbage not 



Persicaria. pungent: spikes slender and erect, the flowers whitish: sta- 

 mens 8: stigmas 3. In very wet places. Perennial. 

 P. &cre, HBK. Smartweed. Herbage pungent: leaves linear or lanceo- 

 late, long-pointed: spikes slender and erect: flowers white or blush: sta- 

 mens 8: stigmas 3. Low grounds. Perennial. 



bb. Sheaths of leaves not hairy, nor the margin bordered. 

 P. Pennsylvdnicum, Linn. Smartweed. Pungent: plant with conspicuous 

 glandular hairs above : leaves lanceolate : spikes short-oblong and erect, the 

 flowers purplish: stamens 8: stigmas 2. Low ground. Annual. 



XIII. EUPHORBIACE.E. Spurge Family, 



Trees, shrubs or herbs, often with milky, pungent juice, some- 

 times poisonous: flowers monoecious or dioecious, mostly apetalous, 

 usually small and inconspicuous. The family is large, in warmer 

 parts of the world. The determination of the genera and species is 

 difficult. Euphorbia and Rieinus will explain the flower structure. 



A. Flowers in a cup-like involucre, wliich imitates a perianth: 



flowers dioecious, without calyx or corolla 1. Euphorbia 



AA. Flowers dioecious, not in an involucre, but in a terminal 



panicle: calyx present, but no corolla 2. Rieinus 



