478 ON SEEDLINGS 



Eupatoria is turbinate and terminated by a great number 

 of hooked processes. That of Acsena ovalifolia (fig. 318) is 

 small, elliptic, and furnished below the apex with two to four 

 strong, spine-like processes with barbed tips. The elliptic 

 receptacle of Acsena myriophylla is covered all over with 

 smaller barbed processes. That of Poterium Sanguisorba 

 (fig. 320) is ovoid and smooth. The cotyledons of all the 

 four types belonging to the Poteriese are slightly auricled at 

 the base so as to fill the space in the seed while at the 

 same time accommodating the radicle. In the tribe Roseae we 

 have a higher development of what occurs in the Poteriese 

 unless we regard the latter as degraded forms of the Eosacese, 

 which is not unlikely, and is, indeed, suggested by several 

 circumstances in addition to those affecting the fruit. The 

 achenes of the different species of Eosa are very numerous and 

 included in an urceolate, ultimately baccate receptacle. The 

 seed in the tribe Prunese is protected by a bony endocarp ; 

 but in the Rosese the enlarged receptacle only is fleshy, 

 while the whole of the ovary wall in Eosa is bony, suberous, 

 or coriaceous in order to protect the seeds. The achenes 

 are covered with short bristly hairs along the dorsal suture 

 in many species. The embryo resembles the Almond in 

 miniature, and the seed being solitary in each achene 

 conforms to the interior of the latter. The seeds and embryos 

 in the tribe Pomese have much in common with all of the 

 foregoing, but they vary somewhat in different genera and 

 species according to modifications of the true fruit or walls of 

 the ovary. In Eosa, as already noted, the achenes or fruits are 

 quite free from one another and from the surrounding hollow 

 receptacle. The carpels in the Pomese vary from two to five and 

 are generally quite free from one another or ultimately separ- 

 able, but they are closely adnate to or united with the inner sur- 

 face of the greatly enlarged, fleshy receptacle. We find two 

 very distinct modifications of the ovary walls of Pyrus. Those 

 of P. Malus are cartilaginous, those of P. communis often 

 very thin and easily broken, while in P. Aria this is 

 always the case. P. germanica and Mespilus grandiflora, 

 often classed together under the genus Mespilus, have a bony 

 endocarp, and the shape of the seed is modified by it. 



