io8 
A RISTOLOCHIA 
modified into stigmatic lobes. Ovary oblong, 6-ridged. Style short, Stigmas 6, united into a 
subglobular concave head. Capsule large, subglobular, and with 6 loculi, with septicidal dehis- 
cence. Seeds oo in each loculus, horizontal, 3-sided, compressed. Endosperm heart-shaped. 
About 160 species, chiefly in the tropical and warm temperate zones. Only British species: — 
* A. clematitis. 
1. # ARISTOLOCHIA CLEMATITIS. Birthwort or Pipewort. Plate 114 
Aristo/ochia clematis Gerard Herb. 697 (1597). 
Aristolochia clematitis L. Sp. PI. 962 (1753); Smith FI. Brit. 947 (1804); Syme Eng. Bot. viii, 91 
(1868); Rouy FI. France xii, 300 (1910); Ascherson und Graebner Syn. iv, 684 (1912). 
leones: — Smith Eng. Bot. t. 398; Ft. Dan. t. 1235; FI. Lond. ed. 2, t. 149; Reichenbach Icon. t. 669, 
fig. 1340. 
Camb. Brit. FI. ii. Plate up Cambridgeshire (E. W. H.). 
Exsiccata : — Billot, 449; v. Heurck et Martinis, vii, 334; Reichenbach, 1148. 
Perennial, glabrous herb. Roots fibrous. Rhizome long, slender, creeping, rather deep in the 
ground. Aerial stems erect, striate, not or little branched, leafy, about 3 — 6 dm. high. Petioles 
about 3 — 5 cm. long. Laminae cordate, entire, undulate, obtuse, rather thick, up to about 7 cm. 
long and 4 — 5 broad. Inflorescence axillary, with about 2 — 8 flowers. Flowers pedicelled ; May 
to July. Pedicels ascending or erect, reflexed in fruit. Perianth pale yellow or buff or greenish 
yellow. Capsule pedicelled, pendant ; August. 
Naturalised, in the vicinity of ruins chiefly, from Kent to Suffolk, Oxfordshire, Yorkshire. 
Naturalised in southern Scandinavia, Denmark, and western and north-central Europe, south-central Europe, 
southern Europe, Balkan peninsula (up to 500 m.) ; central and southern Russia ; Asia Minor to central Asia. 
Order 3. POLYGONALES 
Polygonales Lindley Nixus Plant. 16 (1833); Nat. Syst. ed. 2, 210 (1836); Engler Syll. 101 (1892); 
in Pflanzenfam. Nachtr. 346 (1897); Ascherson und Graebner Syn. iv, 692 (1912); Ochreatae Engler Fiihrer 35 
(1886). 
In some ways, the Polygonales serve as a connecting link of the Petalo'idae and the Centrospermae ; and, in fact, 
some authorities (e.g., Wettstein Handb. Syst. Bot. ed. 2 (1911)) include the Polygonales in the Centrospermae. 
For characters, see page 103. Only family : — Polygonaceae. 
Family 1. POLYGONACEAE 
Polygonaceae Lindley Nat. Syst. ed. 2, 21 1 (1836); Dammer in Pflanzenfam. iii, pt. i a, 1 (1893); 
Ascherson und Graebner Syn. iv, 692 (1912); Polygoneae Jussieu Gen. PI. 82 (1789). 
Shrubs, undershrubs, or herbs. Leaves simple, usually alternate, and (in the British forms) with 
stipular sheaths ( = ochreae) which clasp the stem and axillary bud. Perianth with 3 — 6 segments, 
wholly or partially persistent, becoming more or less adherent to the achene. Inflorescences 
compound, the ultimate branches usually cymose or reduced to a single flower. Stamens peri- 
gynous, 4 — 9. Stigmas 2 or 3, tufted or capitate. Ovary superior, unilocular, uniovulate. Ovule basal, 
orthotropous. Achenes trigonous (when 3 stigmas are present), or bifacial (when 2 stigmas are 
present). Embryo curved or straight. Endosperm present, usually copious. 
About 30 genera and 750 species ; cosmopolitan, but chiefly in the north temperate zone. 
British subfamilies of Polygonaceae 
Subfamily 1. Polygonoideae (p. 109). Ochreae present. Perianth monochlamydeous, usually 
petaloid, with 3 — 6, usually 5 spirally arranged segments ; segments subequal in size. 
Subfamily 2. Rumicoideae (p. 127). Ochreae present (in the British forms), or not. Perianth 
heterochlamydeous, 2-whorled, each whorl with 2 or 3, usually 3 segments, petaloid or sepaloid, 
inner whorl with larger segments than the outer whorl. 
