CARYOPHYLLE.E 209 



As far as structure and form are concerned, there are two 

 leading types in the Order with several modifications. The 

 first is that of Velezia, Dianthus, and Tunica, which have 

 peltate, dorsally compressed or much flattened seeds, with 

 the hilum on the ventral face, and a straight embryo. By 

 far the larger number, however, have reniform, obovoid, or 

 globose seeds, frequently compressed laterally, and attached 

 to the placenta by the edge, which is really the ventral surface. 

 In the latter type the embryo is curved and peripheral, while 

 the cotyledons are incumbent, rarely accumbent. The en- 

 dosperm is mealy and lies in the bend of the embryo, on its 

 sides, or even surrounds the whole embryo in peltate seeds 

 such as those of Dianthus and Tunica. Endosperm is want- 

 ing in some species of Velezia and Dianthus. The whole 

 Order as far as concerns the shape of the seeds and embryo 

 may be considered as consisting of the two leading types 

 above given with their modifications. The first is well ex- 

 emplified in Dianthus plumarius (fig. 196). The seeds are 

 broadly oblong-orbicular, imbricating in one row or series, 

 forming a complete covering to the central columnar placenta, 

 peltate, much compressed dorsally, slightly concave on the 

 ventral face, and elevated on the dorsal aspect, forming a 

 convexity agreeing in outline with the contained embryo, 

 and traversed by a shallow ridge along the whole of the 

 ventral aspect; the hilum is situated a little above the 

 middle ; and the testa, which is smooth and black, is prolonged 

 into a short point at the micropyle, but not winged any- 

 where. 1 



The embryo is straight or slightly curved towards the 

 axis, and transverse to it and enveloped on all sides by a thin 

 layer of endosperm ; the cotyledons are oblong, obtuse and 

 comparatively broad ; the terete radicle is about half the length 

 of the cotyledons, and points into the little projection at the 

 micropyle. D. Caryophyllus, D. chinensis, and D. prolifer, 

 Tunica Saxifraga, and T. pachygona agree in all the main 

 particulars with D. plumarius, but the testa of D. prolifera is 

 muricate or echinulate, and that of Tunica Saxifraga minutely 

 striate-reticulate. 



1 Le Maout and Decaisne, Eng. Trans p. 256. 



