Butters: seeds and seedling of caulophyllum. 31 



ly developed in CaiilopJiyllum, either in the stem or in the root, and 

 that neither in the rhizome nor in the aerial stem of the plant do the 

 bundles fuse into a zone as is usual in dicotyledons, but they re- 

 main permanently distinct, a condition which obtains not only in 

 CaidophyUiim, but generally throughout the Berberidaceae and also 

 in many other families of the Ranalcs. 



Summary. 



The seed and seedling of Caulophyllum thalictroides show several 

 marked peculiarities of form, structure, and behavior. 



The ripe seed consists of a fleshy testa enclosing the very hard 

 endosperm, of peculiar form, which in turn encloses the small em- 

 bryo. The inner integument almost entirely disappears as the seed 

 ripens. 



The embryogeny differs from the ordinary dicotyledonous type 

 rather in the earlier than in the later stages. The embryo develops 

 at first, with very little differentiation of tissues, into a pear-shaped 

 protocorm with a massive suspensor. The cotyledons appear late 

 in the development of the embryo. They are independent in origin, 

 and are symmetrically placed. They display no unusual features of 

 structure or form in the ripe seed, and bear stomata despite their 

 ■entirely hypogean life. 



The germination of the seed is very slow, consisting at first of 

 the gradual intraseminal growth of the embryo, then of a season's 

 •extraseminal growth, which is usually entirely hypogean, and is 

 supported by the large store of nutriment in the endosperm. Dur- 

 ing this growth the blades of the cotyledons together form a pe- 

 •culiar haustorial organ which digests and absorbs the endosperm. 



The first leaves of the epicotyl are usually scale like, and serve 

 to enclose a winter bud. 



The vascular system of the seedling is of a typical tetrarch type, 

 ■each cotyledon furnishing three bundles to the hypocotyl, of which 

 the middle one shows a double structure in the hypocotyl. The 

 vascular tissues coming from the two cotyledons remain distinct 

 almost throughout the hypocotyl. 



The hypocotyl undergoes a very considerable secondary thicken- 

 ing which results in the formation of a continuous zone of xylem 

 surrounding the pith, — a structure not found elsewhere in the plant. 

 By means of this secondary thickening the vascular tissue of the 

 «epicotyl is brought into connection with that of the root. 



