184 



is very open and casts only a light shade. The ends of the 

 branches are pendulous, long, thin, pliant and whip -like. 

 Two branches are shown in Fig. 10. PALEZKIJ has measured 

 roots 19 metres in length. 



The leaves are scattered and pinnate with two linear- 

 lanceolate leaflets densely coated with silky hairs. The 

 rachis sometimes ends in a slender thorn one centimetre 

 long, which frequently persists till the next year. Stipules 

 are absent or represented by two small spines. 



The distal part of the year-shoot probably always dies 

 away before the next vegetative period, also when it is not an 

 inflorescence, which is, however, generally the case (see fig. 

 10). The succeeding year-shoot arises from the middle part 

 of the first year-shoot. Vigorous year-shoots may be bran- 

 ched, but there is no indication that we have here assimilating 

 branches lasting only one summer. The plant has likewise 

 true leaves. 



The flowers are purple and are arranged in terminal 

 racemes. Only the lower flowers in a raceme set fruit; these 

 are also the earliest to develope (April); the later flowers are 

 dried up by the heat of summer. The fruit-bearing branches 

 in tig. 10 show the inflorescence bare above the fruits, and 

 it is seen how few fruits there are compared with flowers. 



The fruit is a yellow, one-seeded, indehiscent, winged 

 "pod" which ripens in May. When ripe it is spirally twisted 

 and this with its lightness enables it to be easily carried off 

 by the wind. The seeds are very hard. According to PALEZKIJ 

 only 2 per ct. of the fresh seeds germinate 

 but they can all be made to do so by cutting 

 the skin. The leaves are isolateral in structure. 

 The epidermis is thick with sunk stomata on 

 both surfaces. Its coating of unilateral hairs 

 is shown in fig. 31. There are about three 

 layers of palisade cells on each side and hardly 

 any spongy mesophyll. The veins have sheaths 

 of hard bast. 



As to the other Ammodendron species, A. 

 Karelini is closely related to the species just 

 described. A. Siewersii, which can hardly 



Fig. 31. Ammo- 

 dendron Conol- 

 lyi. Epidermis 

 with hairs. X 53. 



