THE ANGIOSPERMAE 



1471 



entire embryo and, as in Pistim, extensively multinucleate. In Phaseohis 

 and Cytisus, on the other hand, the cells remain uninucleate but multiply 

 to form a considerable mass of tissue. The cells of these suspensors are 

 rich in starch and there can be little doubt that they take part in the absorp- 

 tion of the endosperm. 



re 



& 





to® ' 



m 



Fig. 1350. — Enlarged suspensorr. in Papilionaceae. A, 

 P/iaseolus multiflorus. Suspensor and embryo not 

 clearly separable. B, Orobiis angustifolins. C, Cicer 

 aiietiiiitm. (After Guigumd.) 



The great majority of plants have relatively small suspensors, con- 

 sisting of a short column of cells without any special differentiation and 

 distinguished only from the meristematic cells of the embryo by their more 

 mature, vacuolated aspect. Indeed in some massive suspensors, where the 

 cells are small, e.g., Phaseohis, there is no sharp division between the sus- 

 pensor and the embryo, at least in early stages. That the purely supporting 

 function of a suspensor is not indispensable is shown by the absence of any 

 suspensor in most Araceae, in many Orchidaceae and in a variety of other 

 unrelated genera. 



The most remarkable suspensors are those which develop haustoria, 

 either within the endosperm, or, frequently in association with poorly 

 developed endosperm, outside the ovule. The simplest form of suspensor 

 haustorium is the enlarged single cell which forms the suspensor in the 

 Caryophyllad Type of embryo. This cell usually has a large and prominent 

 nucleus and has been shown in some cases to contain aleurone grains as a 

 food reserve. A similar enlargement of the lowermost cell of a columnar 



