CKUCIFEILE 139 



testa to accommodate itself to the spirally coiled embryo. 

 The cotyledons are incumbent with their edges to the sides 

 of the seed, oblong, obtuse, entire, forming 1^-2 complete 

 coils with their tips in the centre of the helix. The stout 

 cylindrical radicle extends beyond the cotyledons, occupying 

 the upper and pointed end of the seed, beneath and close to 

 the persistent base of the style. 



Only two strikingly aberrant forms in the Order have come 

 under my observation. These are Schizopetalon belonging 

 to the Sisymbriese, and Lepidium sativum amongst the 

 Lepidinese. Five species of Schizopetalon are recorded, all 

 from Chili. The cotyledons are straight and entire in some 

 of them, but S. Walkeri (fig. 160) has incumbent, deeply 

 bifid, or more often bipartite, spirally convolute, and con- 

 torted cotyledons ; the slender, linear segments being regu- 

 larly coiled, but generally more or less interlacing with one 

 another. The species might be grouped with Bunias, but for 

 the deeply divided and contorted cotyledons. Some botanical 

 authorities have described it as having four cotyledons, but 

 they are mostly united in pairs at the base, and sometimes for 

 a considerable part of their length. The embryo by becoming 

 spirally convolute adapts itself to the interior of the small 

 globular seed, which it completely occupies. The radicle is 

 comparatively large and longer than the cotyledons. Lepidium 

 sativum (fig. 171) is another aberrant form. It has been 

 already described (ante, p. 52). 



Cotyledons. Notwithstanding the diversity of the seeds 

 and fruits in this Order, the cotyledons may be roughly grouped 

 into a few leading types, viz., broad and entire, broad and 

 emarginate, linear, oblong or spathulate, and divided. 



The first type is represented by Matthiola incana (fig. 156) 

 and Cheiranthus Cheiri (fig. 159), but is not confined to seeds 

 having accumbent cotyledons. Instances of broad, rotund, 

 ovate, oval or elliptic, and entire cotyledons may be found in 

 nearly all the tribes into which the Order is divided. In the 

 case of accumbent cotyledons they are situated in the broader 

 plane of the seed, so that their shape and size is easily 

 accounted for, especially in flattened seeds ; but in many 

 cases breadth is attained by a vigorous growth of the cotyle- 



