84 ON SEEDLINGS 



DIPSACE^E. 



Benth. et Hook. Gen. PL ii. 157. 



Fruit and Seed. The ovary of the Dipsaceas is simple, 

 inferior and one-celled, with a solitary, pendulous, anatropous 

 ovule ; but in addition to the true calyx with which it is sur- 

 mounted, each flower of the capitulum is surrounded by an 

 involucel which completely encloses it, and appears like a 

 second or a double calyx. The fruit is an achene surmounted 

 by the persistent rarely deciduous calyx, and is completely en- 

 closed by the involucel, also persistent and either surmounted 

 by a lamina varying greatly in size, or truncate at the apex. 

 The solitary seed, suspended from the apex of the cell, is 

 covered by a thin membranous testa, and contains a thin 

 or thick stratum of fleshy endosperm. The embryo is straight 

 with a superior radicle and oblong or ovate cotyledons. 



The pendulous anatropous ovule characteristic of the Order 

 is represented by a vertical section of the ovary of Scabiosa 

 atropurpurea (fig. 454, A) just after the expansion of the flower. 

 For comparison with this Order the erect anatropous ovule of 

 the Composite is represented in the two kinds of flowers of 

 Chrysanthemum coronarium (fig. 454, B, C). 



The reason for the ovule of the Dipsacese being pendulous 

 and anatropous with a superior radicle has reference perhaps 

 to the exit of the embryo during germination. The involucel 

 is often or always more thickened and coriaceous, and 

 often contracted at the base, making egress there difficult 

 or impossible. The pericarp is thin and easily ruptured at 

 the apex, or is actually open in cases where the calyx is 

 deciduous. This idea is supported by the structure of the 

 fruits in the following species, namely, Scabiosa palsestina 

 (fig. 451), S. atropurpurea (fig. 454), S. australis (fig. 449), 

 S. Gramuntia (fig. 453), S. graminifolia, S. Columbaria, 

 S. Parnassi, S. arvensis, and S. caucasica (fig. 455) ; also by 

 Cephalaria leucantha, C. rigida, Dipsacus sylvestris, D. ferox, 

 and D. inermis. 



A fruit with the calyx deciduous is represented by Dipsacus 



