278 ON SEEDLINGS 



accounted for, since it grows too large to lie flat in the seed. 

 An indication of this condition is seen in Berrya Ammonilla, 

 where the cotyledons become slightly curved at the apex, while 

 in Schoutenia they are involute at the margin. This is 

 precisely what happens in Tilia, and the differences consist in 

 the larger embryo, the greater amount of folding, and above 

 all in the division of the cotyledons into five lobes. The only 

 apparent reason for the lobing is to facilitate folding, not only 

 at the apex, but all round the sides. The seed being obovoid 

 or globose, the embryo assumes the form of a half-closed fist 

 in order to accommodate itself to that shape. 



Cotyledons. The cotyledons may be grouped under four 

 headings, namely, obovate, ovate, lanceolate or oblong-lanceolate, 

 and lobed. The first type is seen in Berrya Ammonilla (fig. 221), 

 which has rotund-obovate, obtuse cotyledons, suddenly tapered 

 into the petiole, five-nerved, reticulate, glabrous except on the 

 principal nerves and the petiole, which are finely pubescent. 

 The hypocotyl is also similarly pubescent not a common 

 occurrence. Before germination they vary according to the 

 shape of the seed from obovate to orbicular with a deeply 

 cordate base, but subsequently lose the latter peculiarity, 

 as in many or most of the Labiatse and in Cuphea among 

 the Lythrarieae. 



Ovate cotyledons are more common, perhaps the commonest 

 form in the Order. Those of Corchorus olitorius (fig. 222) are 

 ovate, obtuse, five-nerved at the base, subfleshy, glabrous 

 except the petiole, which is occasionally thinly pubescent like 

 the hypocotyl. Those of C. capsularis differ in being broadly or 

 rotundly ovate and, sometimes at least, turned to one side of 

 the stem, which would indicate a tendency to become fleshy and 

 functionless, except as a storehouse for reserve-material. Ari- 

 stotelia racemosa agrees more nearly with Corchorus olitorius 

 except in being membranous, indistinctly nerved, and glabrous. 



In some species of Elseocarpus the cotyledons after leaving 

 the seed grow to a considerable size. Those of E. oblongus 

 (fig. 226) are oblong-lanceolate, obtuse, very shortly petio- 

 late, trinerved in the lower half, reticulate, subcoriaceous, 

 glabrous, with red veins, very persistent like the true leaves, 

 about 6 cm. long, and 2-5 cm. wide at the base. Those of 



