ARISTOLOCHIA POLYGONUM 349 



bud, adherent to ovary: stamens 6-12, epigynous, and adherent to 

 base of the styles: ovary 6-celled, pistil 1. A small family of about 200 

 species, sparingly represented in this country. Many of the members 

 have aromatic or bitter-tonic properties. 



A. Low stemless herbs 1. Asarum 



AA. Leafy-stemmed herbs, or woody climbers 2. Aristolochia 



1. ASARUM. WILD GINGER. 



Perennial spreading herbs: leaves large, kidney-shaped, pubescent: 

 flower brown, inconspicuous, borne on a short peduncle arising from between 

 the petioles: rootstocks creeping, elongated, very aromatic. 



A. canadense, Linn. Leaves in pairs, large, renifonn, but more or less 

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

 brown within, consisting of a 3-lobed calyx, adnate to ovary: stamens 12, 

 the filaments 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 tube oddly 

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

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

 mens 6. 



A. macrophylla, Lam. (A. Sipho, L'Her.). Calyx-tube about 1-lJi 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. POLYGONACE^E. BUCKWHEAT FAMILY. 



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

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

 nate: 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 

 achene. Thirty or more genera and about 600 widely dispersed species. 

 Characteristic plants are buckwheat, rhubarb, dock, sorrel, smart- 

 weed. 



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



AA. Root-leaves narrow or not prominent. 



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



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



c. Flowers white and fragrant 3. Fagopyrum 



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



