MODIFICATIONS OF ORGANS. 113 
common in many foreign plants, the flattened siliqua of 
Honesty (Lunaria), the winged nut of the Ash, and the 
paired winged nuts (samaras) of Maples (Acer) being familiar 
examples. 
Avimals unconsciously serve to distribute many species of 
plants. Thus, in many dcenas (Piri-piri) the calyx-limb is 
produced above the angles of the fruit 
into 4 spines bearing barbs at their tips, 
which catch on to passing animals. The 
game mode is attained in Galiwm aparine, 
an English plant naturalised here, by 
barb-like roughnesses of the pericarp; 
in the Bur-reed (Sparganiwm) and others 
by the spiny flower-heads, and in a less 
degree in the seeds of the Carrot, &e. 
In Uneinia, a remarkable and common 
Sedge, or cutting-grass, a specially-pro- 
duced barbed bristle acts ina similar man- 
ner (p. 101). In many foreign plants— 
e.g., Martynia—the fruits or seeds are fur- 
nished with hooked spines or processes rig. 294, Barb of calyx 
by which they catch the hair or fur of of Accena (mag.), 
passing animals. Such fruits and seeds 
frequently become a very serious pest in countries where they 
are abundant. Thus, in Cape Colony and Buenos Ayres the 
annual clip of wool is greatly depreciated in value by the fre- 
quent occurrence in it of such burs or spines. 
Some seeds and fruits become strongly viscid, for the pur- 
pose, apparently, of enabling them to adhere to birds, and thus 
to be transported. This is probably the explanation of the 
remarkably viscid seeds of the Para-para (Pisonia wmbellifera), 
and also of those of Mapau (Piltosporwm). But certainly the 
most common modification of fruits for the purpose of bring- 
ing about distribution of their seeds is that by which they are 
rendered attractive to birds. These eat them, probably in 
many cases swallowing the seeds and passing them undigested ; 
but most likely, in the case of the larger fruits, carrying them 
some distance away, so as, in unmolested peace, to eat the 
fleshy partand drop the stone. Most succulent fruits either have 
a hard stone or contain seeds with a hard testa, so that in either 
ot these modes the pericarp becomes succulent externally 
(Plum, Cherry, Coprosma, &c¢.), and stony in the interior. Such 
fruits are extremely common in New Zealand, where they are 
popularly called berries. Truly baccate fruits, in which all the 
pericarp is succulent, and encloses one or more seeds, are also 
abundant: familiar examples are the Pepper-tree (Drimys), 
Fuchsia, Aristotelia, Poro-poro (Solanum aviculare), and others. 
In Tutu (Coriaria) the same object is attained by the per- 
8 
