1028 Means of Plant Dispersion, [ October, 
MEANS OF PLANT DISPERSION. 
BY E. J. HILL. 
(Continued from August number.) 
III. A third agency in the distribution of plants is that of 
animals. The adaptations of fruits and seeds for this purpose — 
commonly assume the form of hooks and spines, attached in va- 
rious ways so as to secure their adhesion to animals. The at- 
tachment may be straight, but is more often curved, or if straight, ‘ 
‘ah 
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provided with barbs. It may be only a slight hook, as in the — 
curved beak of the fruit of Ranunculus sceleratus, or strongly 
hooked and barbed, as in the cockle-bur (Xanthium sirumarium). 
Several of these contrivances deserve special notice. m 
In the order Leguminosæ, we find the pods of Desmodium can- 
escens, and some others of the genus, covered with hairs having 
incurved tips, and easily adhering to the coat of any passing ani- 
mal. In the order Rosaceæ some forms of Geum, notably & 
rivale, have a persistent style, which, being bent or jointed and 
becoming hard when ripe, serves the same purpose. In Agrimo- 
nia the top-shaped persistent calyx is covered near the upper mar 
gin with hooked bristles which harden at the time of fruiting, 414 
aid in attaching it. Among the Onagracez, the bur-like fruit 
Circzea, or enchanter’s nightshade, is covered with the same kind 
of curved hairs. In the Umbelliferze, our two species of sat T 
Sanicula marylandica and S. canadensis, have the fruit 
coated with hooked prickles. In Osmorhiza, or sweet | catia 
the ribs of the fruit are barbed and cling to an object wi 
siderable force. In the madder family several species of bes 
have fruit in the form of a bur, furnished with hooked bri: 
But some of the best examples of this mode of attac 
in the Composite, in which exist so many cases Ot- 
sion. The cockle-bur has already been mention ; 
lucre of the fruit is closed over the bony nut and clo : 
hooked and roughened prickles, whose power of adhesion 
well known to need description. In the burdock (Lap me 
scale of the involucre ends in an awl-shaped, hooked app“ 
to scatter the heads of fruit, to the great annoyance ' 
herds. In Coreopsis, or tick-seed, the modified pappus ` d 
this result. The flat achenium is tipped with two SHS. 
sharp and stiff, which act as spears to be thrust into the 
