226 ON SEEDLINGS 



about 17 mm. long, and 4 mm. broad. Calandrinia umbellata 

 and Spraguea umbellata agree with the above in the re- 

 lative width of the cotyledons, but the latter are only 2-25 mm. 

 long and 1'25 mm. broad in Spraguea. They are oblong- 

 ovate, obtuse, sessile, and subfleshy. There are a few notable 

 points to be observed in the germination of the seeds. In some 

 cases the testa splits along the side of the cotyledons, which, 

 meeting with little resistance, emerge here, contrary to the 

 usual rule in seeds that the radicle is first protruded. 

 They continue to grow till the endosperm becomes exhausted 

 through the medium of the radicle, when the seedling, unable 

 to make any further progress, dies, unless the conditions are 

 favourable for the emission of adventitious roots, whereby it 

 can lay hold of the soil and become established. When how- 

 ever the seeds have been properly covered with soil the radicle 

 emerges first, the arching hypocotyl pulls the cotyledons out of 

 the testa, and after it has become straight these unfold to the 

 light. The testa is however frequently carried up on the 

 cotyledons, when it exhibits a vertical cleft of considerable 

 size, thus allowing the escape of the cotyledons, which are 

 comparatively broad, oblong, obtuse, and sessile. In the 

 mature seed the cotyledons are long, narrow, and quite typical 

 of the Order ; but after germination or during it, they develop 

 more in breadth than length, and remain comparatively short. 

 Sown under glass they germinated in ten days. 



Several species of Calandrinia, including C. pilosiuscula 

 and C. speciosa, agree with Claytonia in the narrowness of 

 their cotyledons, also some species of Talinum, and it is pro- 

 bable that several other genera of the same habit have similar 

 cotyledons; in C. umbellata they are broader, and some 

 other species of Calandrinia which differ in habit and have 

 broad, fleshy, mostly radical leaves, may possibly have differ- 

 ent cotyledons. 



Portulaca grandiflora, Hook. 



Hypocotyl erect, terete, reddish, glabrous, 10-15 mm. 



Cotyledons oblong-oval, obtuse, fleshy, glabrous, stained with 

 red underneath, shortly petiolate, about 17 mm. long including the 

 petiole, 4 mm. broad. 



Stem herbaceous, erect in the early stages, but afterwards pro- 



