NYCTAGINE.E 403 



Those of 0. ovatus are larger, more decidedly auricled at the 

 base, densely hairy, and sometimes at least unsymmetrical. 

 The first pair of leaves are lanceolate, showing only a 

 midrib, and are hairy like the cotyledons. The latter in 

 0. elegans are more roundly reniform, trinerved, glabrous 

 and, like the others, very shortly petiolate. As in 0. ovatus 

 the short hypocotyl becomes fleshy and tuberous at a very 

 early age. The first pair of leaves are lanceolate, succeeded 

 by others which are ovate and glabrous like the cotyledons. 

 A slight variation occurs in 0. nyctagineus which has suborbi- 

 cular, trinerved, glabrous, unequal cotyledons. The lamina 

 of the larger ones measures about 1-5 cm. long, and 1*35 cm. 

 wide, while that of the smaller one is 1-4 cm. long, and 1-3 cm. 

 wide. Both are cuneate at the base. 



The species of Abronia differ considerably from the above, 

 both in the form of the cotyledons before and during germi- 

 nation, and in their behaviour afterwards. One of the 

 cotyledons is almost aborted in the seed and remains small 

 for some time after germination but in A. umbellata at least 

 it afterwards becomes the largest and grows like a leaf, attain- 

 ing the shape of the latter. The lamina of the larger one 

 eight days after germination is oblong, 8-8 - 5 mm. long, and 

 4-5-6 mm. wide; twenty-eight days after germination it is still 

 of the same shape, but is 1*4-1'45 cm. long, and 9 mm. wide. 

 The lamina of the smaller one eight days after germination is 

 obovate, 1'25 mm. long, and 1 mm. wide ; twenty-eight days 

 after germination it is 1 -4-1*8 cm. long, and 8'75-lQ mm. 

 wide above the middle. The leaves are alternate, but the 

 primary ones are nearly opposite. The first four are oblong, 

 somewhat cuneate at the base, and rounded at the apex. The 

 full-grown cotyledons of A. arenaria are very unequal. The 

 larger one is oval, 1-4 cm. long, and 8'75 mm. wide, with 

 a petiole 3-4 cm. long, while the smaller one is obovate, 

 5 mm. long, 3'75 mm. wide, and the petiole 2-2-6 cm. 

 long. The leaves are opposite, but so unequal in size 

 that they appear alternate during development in the bud. 

 They are finely glandular-pubescent, and the first four at least 

 are oval like the larger cotyledon. The ultimate ones are 

 broadly ovate or suborbicular, unequal both in lamina and 



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