272 ON SEEDLINGS 



leaves of the adult plant in the Kew specimens are more poly- 

 morphic than those of the seedling ; they are broader than long, 

 or suborbicular or oblong-emarginate. sometimes subcordate at 

 the base, or they are ovate, or obovate-oblong. The cotyledons 

 of Ipomoaa Nil are also trinerved from the base, but they are 

 rather less deeply divided, unequal in size and have wider lobes. 

 The first three leaves are cordate, acuminate, and five-nerved 

 from the base. I. dissecta (fig. 542) has also unequal, tri- 

 nerved cotyledons, but they are more deeply auricled at the 

 base, and a second pair of lateral veins arise a little above the 

 base making them almost five-nerved. Their petioles are 

 considerably elongated to compensate for the shortness of the 

 hypocotyl above the soil. The first internode of the stem is 

 but little developed, and the first leaf five-toothed and almost 

 or quite rudimentary. The second leaf is five-lobed and 

 several times larger, but yet very small. The third to the 

 sixth inclusive are palmately five-nerved and -partite with 

 rhomboid-lanceolate segments. 



A fourth type is exhibited by those species having five 

 to seven nerves proceeding from the base of the lamina. 

 Ipornoaa hispida (fig. 541) has cotyledons resembling those of 

 I. Nil in outline and depth of division, but they are more 

 nearly equal, and five-nerved at the base. The first two leaves 

 are cordate, acute and seven-nerved at the base. The cotyle- 

 dons of I. Eoxburghii are larger, rather more deeply bifid, 

 and seven- nerved at the base. The first leaf is cordate, 

 acute, and the next two are similar, but angled at the 

 sides or incipiently lobed. All are five- to seven-nerved at 

 the base. The cotyledons of Argyreia speciosa are remark- 

 ably similar to those of Ipomcea Eoxburghii. The first 

 leaf is however cordate-acuminate, and the second cordate- 

 acute. The hypocotyl of Argyreia cuneata is subterranean, 

 fleshy, stout and inseparable from the upper part of the root. 

 The cotyledons are faintly seven-nerved at the base, and have 

 long, slender petioles partly buried in the soil. The inter- 

 nodes of the slender, flexuose stem are elongated. The first 

 leaf is broadly oval and rounded at either end ; the following 

 three are more elongated and proportionately narrower. The 

 cotyledons of Lettsomia aggregata are divided more than half- 



