PLATE 278. 



Xanthium STRUMAEiuM, Linn. (Sp. PL edit. 1, p. 987.) 

 Natural Order, Composite!. 



A tall monoecious annual with large palmate or subentire leaves, and seed- 

 vessels -with hooked spines; the whole plant 1 to 3 feet high. Stems erect, 

 branching, scabrous. Leaves alternate, petiolate, exstipulate, palmate or deeply 

 lobed, margins finely and unequally crenato-serrate, more or less scabrid on both 

 surfaces; primary veins prominent beneath, less so above, lamina reaching to 7 or 

 8 inches long or wide ; petiole scabrous, channelled above, reaching to 6 inches or 

 more in length. Inflorescence axillary and terminal, the male heads globose, 

 pedunculate, female heads ovoid, subsessile. Male heads 2 to 3 lines in diameter, 

 many flowered, involucre of a few linear-oblong scales, peduncle 2 to 3 lines long, 

 with a minute subulate bract at base. Corolla 5-toothed. Stamens 5, monad el- 

 phous at base, anthers linear-oblong, membranous-tipped, the membrane inflexed. 

 Female heads more numerous than the male ones, clustered in the axils, and having 

 at base several linear-oblong ciliate bracts, in two or three rows, lengthening in 

 fruit, the two innermost ones very large and consolidated into a hard mass, which 

 externally is thickly clothed with hooked bristles, and terminates in two conical 

 appendages, through which the two lobes of the stigmas project. Corolla 0. 

 Ovaries 2, enclosed in a cell of the hardened involucre. Fruit a prickly burr, 

 I inch or more long, 2-celled, cells 1-ovuled. 



Habitat .- Natal : In waste places on coast and midlands. 



A noxious weed which is now included in the same Law as X. spinosum. It 

 is found in most tropical and subtropical countries, and in Australia is known as 

 " Cockle Burr " or "Noogoo Burr." In addition to the fact that its burrs are 

 quite as injurious to wool as those of X. spinosum, it is reported also to have 

 poisonoiTS or deleterious properties, this is denied by some writers, and there is 

 still much doubt on this matter. In Natal the plant is certainly spreading, and in 

 Queensland the Government botanist is reported to have said " I well remember 

 when £50 would have stamped it out in my colony, now it would take untold 

 wealth to do it." It is therefore most important that every care should be taken 

 to rid the colony of what may prove to become a serious pest. 



Unfortimately the seeds retain their vitality for a considerable time, it should, 

 therefore, never be allowed to reach the seeding stage, but the young plants should 

 be destroyed before flowering, or farmers may have cause to regret their apathy 

 in the matter. The genus includes 4 species which have been unnecessarily much 

 increased by authors, and its native country is unknown, but is probably America. 



Fig. 1 , female flower head ; 2, longitudinal section of same ; 3, ovary, style 

 and stigma ; i, male flower head ; 6, calyx of male flower opened ; 6, stamens ; 

 all enlarged. 



