Xanthium.] LXII. COMPOSITAE. 535 
Pappus none. Coarse se gi, alternate. Flower-heads in axillary 
or terminal clusters or short rac 
A genus of two or perhaps three species, natives of the Mediterranean region and the 
m or one perhaps of Chilian origin, all now spread as weeds over many parts of the 
*l. X, spinosum, Linn.; DC. Prod. v. 523. A rigid much-branched 
annual of 1 to 2 ft., iaaea with numerous strong trifid spines usually op- 
posite in pairs or rarely solitary, divaricate, placed at the base of the leaves 
E rather within the petiole. Leaves lanceolate, trifid, with the central lobe 
uch longer than the lateral ones, slightly scabrous above; white-tomentose 
Benet Flower-heads in axillary clusters or almost solitary, the upper 
ones male, the rigs female; these are sessile, forming when in fruit oblong 
burrs about A in. long, covered with hooked prickles, the terminal conical 
beaks cH short, often both reduced to mere tubercles or one only 
slightly elongated. 
An exceedingly troublesome weed, in warm "s situations, supposed to be of Chilian 
origin, now antonio g southern paraa and many warm countries, firs t observed in ger 
abont 1852 and now said to be v ery abundant in pany Get res of M ape rior of Qu 
. S. Wa Ae es, and Victoria, to the great detriment of the wool. 
. Taree VI. Hextanruns.—Leaves opposite or rarely alternate. Flower- 
heads usuall heterogamous, the florets of the circumference female or neuter 
and ligulate, or ra rely irregular or wanting, the disk-florets hermaphrodite or 
übular, 4- or 5-toothed. Receptacle bearing chaffy often rigid scales 
‘between the florets. Feis obtuse at the base. Style of the Senecionide 
bs pons that of the Asteroidee. Pappus of stiff awns or short scales 
30. SIEGESBECKIA, Linn. 
3 nvolucral bracts in about 2 rows, the outer ones EE spread- 
‘ng, glandular- hispid, the inner ones ovate or oblong, half enclosing the 
achenes, glandular-hispid on the back. Receptacle chaffy, the scales half 
enclosing the achenes,  Ray-florets female, shortly ligulate or irregularly 2- 
or 3-lobed. Disk-florets hermaphrodite, fertile, p 5-toothed. Anthers 
obtuse at the base. Style-branches short, som what flattened, very obtuse 
or rarely tipped with a small glandular cone. Achenes somewhat turgid, 
‘Usually curved, Tappa none.—Herbs with opposite leaves. Flower-heads 
ver the warmer regions of the globe, the 
Lo SG pho he eg As calgon in the Old we d. ` 
|. 8. o entalis, Linn.; DC. P Prod. v. 495. A pubescent branching 
her Sf a d. 1 to 2 ft. high. Leaves from broadly ovate-triangular to 
lanceolate, 11 13 to 2 in. long or the loe oues langer; the petioles variable in 
i length, usually dilated upwards but not at the base Flower-heads 3 to 6 
Ae oad, in a dichotomous leafy bas cle. Outer involucral bracts often 
.* 9r 5 lines long and covered with gland- -bearing hairs, but sometimes shoiier 
p 
