ADArTATIONS FOU DISPERSAL OF FRUIT & SEEDS 24.?, 



1. DiSTRir.UTiox p.Y Wind. 



The dispersal of fniits and seeds by the wind is per- 

 haps the most common means emph^3'ed and two distinct 

 metliods are found in natnre (a) plants in which the 

 fruits open allowing the enclosed seeds to escape and 

 (b) plants in which the fruits with tbeir contained 

 seeds are carried away by the wind. 



Plants in irliich fJtc fiiiifs open to allow the seeds to 

 escape : — 



(a) The seeds are excessively small and light and are 

 blown away like fine dust. (PI. III. fig. 12.) This type 

 of seed is found usually in species of Orchidaeeae^ 

 Ericaceae and CanjoplujUaceae. In plants belonging to 

 the above Natural Orders, the mature fruit opens by slits 

 or pores, the ripe seeds lie loose within the fruit and 

 when the fruit is violently shaken by strong winds the 

 seeds escape and are blown away long distances. Some 

 idea of the size of these seeds can be formed when we 

 find that about 26,000 seeds of Erica coccinea only weigh 

 one gramme. This estimation was made by Dr. Marloth. 



(b) A somewhat similar method is found in i)lants 

 which have dry fruits. In these plants the fruits open 

 only sufficiently to allow the seeds to escape if the 

 fruit is violently shaken. (PL III. fig. 1.) Good examples 

 are found in many Iridaceae and Liliaceae in which the 

 seeds are flattened or Avinged and suitably adapted for 

 wind-dispersal. The common " Stinkblaar " (Datura 

 strautouiiint) is a plant of this type. The fruits are 

 spiny; passing animals shake the fruits so that the seeds 

 are thrown out. A similar type of fruit is also found in 

 Erytlirina acantliocarm (PI. III. fig. 25.) The common 

 '^ Khaki Weed'- [Tagetes minata) brings about the same 

 result by different means. The involucre is in the form 

 of a tube and the fruits lie loose within the involucre. 

 Animals brushing past the bushes cause the fruits to 

 fall out. Each fruit is armed with a few terminal spines 



