The Scottish Naturalist. 261 



has such a wing of large size, but in some tropical species (e.g., 

 Bigtioniacece) it reaches a breadth of over an inch. The firs 

 and various other conifers have a large wing directed obliquely 

 upwards and to one side ; probably most persons have noticed 

 how far these seeds are carried by even a moderate breeze before 

 reaching the ground. The effect may also be understood if one 

 examines moorlands or natural pastures for some distance 

 around a fir wood. Young fir-trees will be found to be abun- 

 dant in such localities, though cropped so close to the soil in 

 pasturage that they need to be looked for. 



In other plants the seeds bear a coat of hairs over the sur- 

 face (as in the cotton plant), but of this we have no conspicu- 

 ous native example. Among willows and poplars, and also 

 in the willow herbs (Epilobium), each seed bears a tuft of hairs 

 at one end, and the seeds themselves are small and light, so 

 that they are wafted on by the faintest breeze. The disper- 

 sion of the seeds from a clump of willows or of poplars is often 

 too noticeable to have been overlooked by even the least 

 observant. 



Among one-seeded indehiscent carpels we meet with adapta- 

 tions very similar to those just noticed among seeds, and also 

 with others of a different nature, all serving the same use in the 

 economy of the plant. Carpels are frequently so like seeds in 

 appearance that they are often called seeds (as in the so-called 

 carraway seeds, or those of the daisy, of grass, &c), and a care- 

 ful inspection may be needed to show their true nature. The 

 readiest test is to cut through the suspected body, in which case, 

 if it is a carpel, the seed will be found inside it. Such carpels 

 {e.g., those mentioned above) are frequently small, but they are 

 very rarely small enough to be carried about like dust, and 

 equally rarely are rendered light by means of empty space in 

 the walls of the carpels (e.g., in Myagrum and Valeria nrfla 

 species). On the other hand, one-seeded carpels are often 

 winged. The most rudimentary adaptation of this kind is seen 

 in plants where the carpels are flattened as in Heracleum, with- 

 out being prolonged into a noticeable wing. From this stage 

 all intermediate forms occur up to the bilateral wing of the elm 

 and birch, and the large unilateral wing of the maples. The 

 ash-tree also has a long wing projecting beyond the seed-bearing 

 portion. Similar winged carpels are found in many exotic 

 plants of different genera and orders. A rarer form of wing 

 occurs in Paliurus aculeatus, in which it encircles the carpel like 



