234 Agricultural Gazette of N.S. W. [2Iar, 2, 1908. 



The Weeds of New South Wales 



A Tumble-weed {Ahiarantua albas, L. ). 



J. H. MAIDEX, 



(joveriiinciit liotaiiist and Director of tliu Botanic CJanluns, Sidney. 



Description of ./. a lb us. 



("Tumble-weed," or " White Aiii;ir;uitli.'") 

 Ax erect, glaV)i'(jus, piile-i^i-eon niiiiual licrl), alxxit (i iiiclies to i' foot liii,'h, 

 witli slender, ascending, rathoi' whitish l)ranches. 



Leaves alternate, from oblong to obovate, from tnidoi- .', to 1.', inch h)iig, 

 iiarro\v(-d into a sloiidci- petiole, the top generally with a tine ])oint (the 

 jirolongation of tho mithih liov<nid tlio l)lade). 



Flowers often unisexual, several t'\getlior in small axillary clusters shorter 

 thaii the leaves, commonly not longer than tho petioles, sm-roundod bv three 

 subulate pungent-pointed sj)reading bracts. 



Sepa/s, 3, much shorter than the bracts, meml)rauous, whitish. 



Sfcujiens, 3. 



Petals, none. 



Fruit, a wrinkled utricle, opening cii-cumsciss, with a single smooth and 

 shining dark seed. 



The leaves fall away in autumn, and on the plains the plant, thus denuded, 

 is freely uprooted and lilown before the wiiul, whence the American popidar 

 name " Tumble-weed." 



It is stated to be often mistaken in America for tho dreaded "T'ussian 

 Thistle" (a form of Sahola kali). 



It has largely been diffused in the United States through tlirty pasture and 

 lawn grass seeds. It is one of the most pernicious weeds in the United 

 States, and althougli it does not occur in New South Wales in the same 

 abundance, it is a weed to be dreadefl and fought against. 



An enemy in Ohio is a white mould, Cystopus bliti (Biv.) Lev., which also 

 attacks the beet. It is an annual, and the onlv wav to destrov it is to pull 

 it up before it rijiens its seeds. 



Common in waste and cultivated ian'ls throughout the greater part of 

 North America. 



It is now spread nearly o\-er the whole glolie, but is indigenous onlv in 

 North Amei'ifa, and probably oidy in trojjical North xVmerica. 



In New South AN'ales T have only received it fi-oni the Riverina. but do not 

 doubt that search will iind its invasion to lie much more extended than that. 



Explanation of Plate. 



1. l'"iuit-bearing branch (much reduced). 

 1a. Twig (natural size). 



2. Part of same enlarged, siiowing a fruit in axillary clusters supported by bracts. 



3. Fruit, a membranous utricle o])ening circumsciss when ripe. 



4. iSeed, a single one in each fruit, very daik red (much enlarged and natural size). 



5. Leaf much enlarged. 



