West. The flower buds just before opening have a large drop of liquid resin 

 on them, and, as the plants frequently grow along trails, they are trouble- 

 some from soiling ladies' dresses. 



Of the FLEABANES, the Horseweed, Erigeron canadensis, L., is the most 

 abundant and widespread, its tall spire-like stems being seen on stubble left 

 for summer fallowing, on neglected land and in waste places in all parts of 

 the Dominion. The Daisy Fleabane, Erigeron annuus, Pers., with coarsely- 

 toothed leaves and the Rough Daisy Fleabane, Erigeron strigosus, Muhl., 

 which has entire leaves, are common clover-field weeds in all parts of Eastern 

 Canada. The small seeds are carried in grass seeds. 



Among the EVERLASTING FLOWERS some species of Antennaria and Gna- 

 phalium injure pastures by crowding out the grasses. By breaking up the 

 sod these can be destroyed. 



A small natural group consisting in Canada of the Ragweeds, Marsh- 

 elders and Cockleburs, has been separated recently from the Aster family and 

 called the RAGWEED FAMILY (Ambrosiacece) ; but in this publication it is 

 thought better to keep it in its old place near the Sunflowers. 



Some kinds of WILD SUNFLOWERS are noticeable weeds in the Prairie 

 Provinces. In Manitoba the Many-flowered Prairie Sunflower, Helianthus 

 Maximiliani, Schrader, and the Black-headed Sunflower, H. rigicius, Desf., 

 are the most abundant; but the Wild Artichoke, Helianthus doronicoides , 

 Lam., is the most difficult to eradicate. For all of these, early summer fal- 

 lowing is the best method. The seeds are often found among western grain. 

 In the Many-flowered Prairie Sunflower, they are [Plate 55, fig. 60 natural 

 size and enlarged 4 times] about of an inch long, variable in shape, 

 but mostly narrowly oblong egg-shaped in outline, flattened and rather an- 

 gular, grooved lengthwise, brown, cross-mottled with irregular zigzag white 

 lines ; the apical and basal scars are both conspicuous, the latter rather 

 oblique and indented in the middle. 



On the western plains are many species of WORMWOOD, Artemisia, which 

 are spoken of collectively as Sage brushes. Two of these, the Pasture Sage, 

 Artemisia Ludoviciana, Nutt., and the so called Sweet Sage or Lesser Pasture 

 Sage, Artemisia frigida, Willd., are sometimes troublesome by infesting home 

 pastures, where the grass has been eaten close, necessitating the breaking up 

 of the sod. The best known of the Wormwoods is the FALSE-TANSY, Artemisia 

 biennis, Willd., a biennial which occurs in all parts of Canada and although 

 very easily eradicated is a very unsightly weed when growing, as is often 

 the case, among grain crops on stubble. The remarkably small seeds, iV 

 of an inch, are dark brown, egg-shaped, wrinkled lengthwise and with a 

 conspicuous pale-coloured ring-like basal scar. [Plate 53, fig. 18 twice 

 natural size and enlarged 8 times.] 



Closely allied with the Thistles is a weed which is rather abundant in 

 meadows in the Maritime Provinces. This is the KNAPWEED, Centaurea 

 nigra, L., a rather coarse perennial with thistle-like flowers, over one inch 

 across and 1| inches high. The involucre or calyx-like whorl of bracts sur- 

 rounding the flower-heads is spherical and composed of black-fringed scales. 

 The seeds are about J of an inch long by about half as wide, taper- 

 ing to the base, cut off squarely above. On one side of the base, but above 

 the end, is the large conspicuous basal scar; the large apical scar covers the 

 whole of the top of the seed, and is surrounded by the pappus of two or 

 three rows of short, flat bristles. The seeds (achenes) [Plate 56, fisr. 63 

 natural size and enlarged 4 times] are slightly angular, somewhat flattened 

 and striped lengthwise on their shining gray surface with pale ridges ; the 

 whole seed is sparsely hairy. The Knapweed is palatable to all stock and 

 in no way injurious, but is unsightly and takes the place of the more valu- 

 able true grasses. 



48 



