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THESIUM 
British species of Thesium 
1. T. humifusum (see below). Perennial. Bracts and bracteoles often subequal. Perianth 
with simple veins, segments flat. 
2. [+T. humile (see below). Annual. Bract twice as long as the bracteoles. Perianth with 
veins with conspicuous branches, segments incurved.] 
I. THESIUM HUMIFUSUM. Bastard Toad-flax. Plate hi 
Linaria adulterina Johnson in Gerard Herb. ed. 2, 555 (1633); Ray Syn. ed. 3, 202 (1724). 
Thesium humifusum DC. Ft. Fratice Suppl. v [ou vi], 366 (1815); Syme Eng. Bot. viii, 88 (1868); 
Rouy Ft. France xii, 293 (1910); Ascherson und Graebner Syn. iv, 657 (1912); T. divaricatum var. humifusum 
Duby Bot. Gall. 408 (1828). 
leones: — Smith Eng. Bot. t. 247, as T. linophyllum\ Reichenbach Icon, xi, t. 542, fig. 1153. 
Camb. Brit. FI. ii. Plate ///. (a) Flowering branches, (b) Flowers (3 enlarged). Cambridgeshire (A. H.). 
Exsiccata : — Billot, 636. 
Perennial, hemiparasitic herb. Roots slender, much branched, with suckers attached to various 
host-plants. Stem more or less branched, decumbent, up to about 15 cm. long, angular, ridges 
rather rough. Laminae linear, entire, acute, 
1 -nerved or feebly 3-nerved, rather glaucous. 
Bracts and bracteoles often subequal, leaf-like. 
Flozvers pedicelled ; June to August. Perianth 
white, persistent, about 5 mm. in diameter 
at the top when open ; segments 5, about as 
long as the tube, flat when in flower, incurved 
in fruit, each with a tooth on each side near 
the base. Stamens 5, antisepalous. Style 
rather long. Stigmas 2 or 3, very small. 
Seeds oval to subglobular, 5-angled, striate. 
Calcareous pasture, on Chalk, calcareous 
sands, and Oolitic limestone. From the 
Channel Isles, Devonshire, and Kent to 
Gloucestershire and Norfolk. 
Belgium, Lorraine, France, Spain. The 
allied T. italicum DC. Prodr. xiv, 644 (1857) 
occurs in Corsica, Italy, and Sardinia. 
Map 14. Distribution of Thesium humifusum in England 
[2. tTHESIUM HUMILE] 
Thesium humile Vahl Symb. Bot. iii, 43 (1794); Babington Manual 261 (1843)!; Rouy FI. France xii, 
288 (1910); Ascherson und Graebner Syn. iv, 661 (1912). 
leones: — Reichenbach Icon. t. 542, fig. 1153. 
Exsiccata: — Bourgeau (PI. Esp.), 436 ; Huter, 1143; Porta et Rigo, 318; Sintensis et Rigo, 7; Todaro, 282; 
herb. Babington in Herb. Univ. Cantab. 
Annual. Stem decumbent or ascending, grooved, much branched from below. Branches very 
leafy, suberect. Laminae short, linear, 1 -nerved, denticulate above. Flowers solitary, subsessile ; 
May and June. Bract twice as long as the bracteoles. Perianth-segments with conspicuously branched 
veins. Achene elliptical, shortly pedicelled. 
Two specimens of this species were gathered by Babington, in 1829, near Dawlish, Devonshire. Syme {Eng. 
Bot. viii, 89 (1868)) does not regard it as indigenous. 
Mediterranean region : Spain to Asia Minor, northern Africa, and the Canary Islands. 
