191 i.J Identification and Eradication of Weeds. 289 



cornfields on most soils, though it would appear to flourish 

 best on the chalk, on heavy land. A North Lincolnshire 

 correspondent informs the writer that the weed is there 

 plentiful on the strong clay of the wolds, but is less common 

 on the light soils, while it occurs in summer fallow wheat and 

 winter sown barley more than in spring corn. In Hertford- 

 shire and Bedfordshire also the Corn Buttercup is char- 

 acteristic of clay soils. 



Fruits. — The fruits (Fig. 1, a) achenes or nutlets of the 

 Corn Buttercup are brown in colour, rather large ("2 to 

 '24 in. long by '16 in. broad by '04 in. thick — 5 to 6 mm. long 

 by 4 mm. broad, by 1 mm. thick), woody, flat and unsym- 

 metrical, with hooked spines on either side, the larger spines 

 to the outside, and from their appearance the weed is some- 

 times termed "watch wheels." The spinous processes may 

 serve both to distribute the pest and to protect the seed and 

 ensure germination. The fruits occur commonly in samples 

 of cereal grains, and also in unmilled sainfoin, which they 

 resemble in size and colour. One hundred large air-dried 

 two-year-old achenes weigh 1*219 grams, equal to about 

 37,300 to the pound.* 



Seedlings. — The early stage seedling (Fig. 1, b) shows the 

 root and base of the hypocotyl (the portion between the root 

 and the cotyledons) to be markedly divided into three or four 

 branches or rootlets. The hypocotyl is white, stout and 

 smooth, and slightly swollen at the junction with the cotyle- 

 dons, or seed-leaves. The cotyledons themselves are pale 

 dull green both above and below, smooth, oval or round-oval, 

 contracting below into a broad and almost flat petiole (leaf- 

 stalk) which is slightly hollowed above. Three distinct veins 

 are visible below, running from the base towards the apex,' 

 one being in the centre and the other two curving outward on 

 either side. At first the cotyledons are almost vertical, but 

 expand until horizontal; they are J — 7 3 o in. long, and J — \ in. 

 broad (6 to 7*5 mm. long, and 4 to 5 mm. broad). 



A little later stage (Fig. 1, c) shows the seedling to have 

 a tufted and fibrous root, while the hypocotyl is white or 

 slightly tinged reddish-brown above. The first leaves are 

 radical, and almost triangular or wedge-shaped, the broad 



* Landw. Samenktmde, C. D. Harz, 1885. 



