AKIRTOLOCHIACE.E — POLYGONACE^ 317 



flower brown, iuconspli'uous, borne on a short peduncle arising from lietween 

 the petioles: rootstocks creeping, elongated, very aromatic. 



A. Canadense, Linn. Leaves in pairs, large, reniform, but more or less 

 pointed at tip, soft-hairy with a silky finish: flower greenish outside, 

 purple-brown within, consisting of a '!-lobed calyx, adnate to ovary: 

 stamens 12, the tilanients longer than the anthers. Common in rich woods. 

 April, May. 



2. ARISTOLOCHIA. Dutchman's Pipe. 



Herbs or tall vines, with alternate, petiolate leaves, cordate, entire 

 and palmately nerved: flowers irregular, the calyx tubular, the lube oddly 

 inflated above ovary and contracted at throat, shaped like a much-bent 

 pipe, the margin reflexed or spreading, 3-6-Iobed or appendaged: sta- 

 mens 6. 



A. macrophylla, Lam. (.4. Siplio, L'Her.) Calyx-tube about 1-1% in. 

 long, curved to resemble a Dutch pipe, the margin spreading, brownish- 

 purple: leaves large, smooth, dark green, round kidney-shaped. Wild in 

 rich woods; May; often cultivated. 



XII. POLYGONACEJi:. Buckwheat Family. 



Herbs, mostly veith enlarged joints or nodes and sheaths (repre- 

 senting stipules) above them : leaves simple and usually entire, 

 alternate : flowers small, apetalous, usually perfect and generally 

 borne in spikes or dense clusters : stamens 4-12, attached to the 

 very base of the 3-5-merous calyx : ovary 1-loculed, ripening into a 

 3-4- angled akene. Thirty or more genera and about 600 widely dis- 

 persed species. Characteristic plants are buckwheat, rhubarb, dock, 

 sorrel, smartwsed. 



A. Root-leaves 1 ft. or more across, rounded 1. Jilieum 



AA. Root-leaves narrow or not prominent. 



B. Calyx of 6 sepals, often of two kinds 2. Bumex 



BB. Calyx of 5 (rarely 4) sepals, all alike. 



C. Flowers white and fragrant .3. Fagopyrutn 



cc. Flowers greenish or pinkish, not distinctly fragrant. 4. Polygonum 



1. EHl:UM. Rhl'bakb. 



Very large-leaved perennials, sending up stout hollow flower-stalks in 

 early summer which bear smaller leaves with sheathing bases: sepals G, all 

 alike, withering rather than falling, and persisting beneath the 3-winged 

 akens: stamens 9: styles .3. Old World. 



R. Rhap6nticum, Linn. lihuhnrb. Pie-pJaut. Figs. 78, 79. Leav<»s 

 1 ft. or more across, the thick petioles eaten: fls. white, in elevated 

 panicles. 



