VASCULAR ANATOMY OF THE SEEDLING OF 



MICROCYCAS CALOCOMA 



COXTRIBU 



Helen Angela Dorety 



(WITH PLATES V AND Vl) 



HISTORICAL 



DeCandolle (5) i n the first account of the genus Microcycas 



expresses 



mediate between Dioon and Zamia 



:■: 



Microcy 



taxonomic 



aldwell and Baker (i), who succeeded in procuring material 

 n>m Cuba. The only part of their description which concerns us 



r <ns the stat nmont tw *u„ ^ i • , , i_.j__ 



In 



stem 



• • 



"eproduct 



some 



Certain 



r — uuw ^naiacLers oi me emDryo ana seeanng. i^eiiam 



have be* k~! ^ naturall y overlooked in so comprehensive a work, 

 e en brought to light by a more detailed studvhavine the 



INVESTIGATION 



see^ an ^ rst placc > il is not the root which is seen to emerge from the 

 ^ senuenc 6 ^ d ° Wnwa . rd ' as described and pictured by this author; 

 toat descr'hV CVents m tne P roc ess of germination is the same as 

 °> Ta ds whi h f ° r Cerat02amia (7), the same which occurs in the other 

 species of 7 • haVG germin ated, Dioon edule, D. spinulosum, and 

 e,on gating ~ ai K la ' The r ° 0t is not ?* forme d when the base of the 

 micr opyIar r }0 FUptUres the seed coat in the small, less indurated, 

 disk constitu? 011 ' ^ hen li emer § es ' h sti11 bears the smal1 brown 

 thf a riy sta<* mS thC ° nly remains of the coleorhiza, an organ which, in 

 "wophyte ^ Th° f thC embr y°S en y, is b y far the larger portion of the 

 the soil. Th UnitCd cot >' ledonar y stalks bend downward toward 

 i»] " e root ma y not pierce the coleorhizal disk until the latter 



[Botanical Gazette, vol. 47 



