MICROSCOPIC STRUCTURE OF WEED SEEDS 



561 



UMBELLIPERAE, PARSLEY FAMILY. 



Sweet Cicely {OsmorrMza longistylis (Torr.) D. C). 



The epidermal ceUs are longer than broad, the outer walls are 

 thickened, five to six rows of thin-walled parenchyma cells occur 

 underneath the epidermal layer ; the ribs contain the vascular ele- 

 ments, thiek-waJled sclerenchyma cells; the testa consists of a 

 layer of thin-walled parenchyma cells, p, followed by a layer tan- 

 gentially elongated and another of large parenchyma cells, p^, and 

 the compressed nucellus, n^ The endosperm consists of large thin- 

 walled cells. 



Fig. 428. Microscopic structure of some Umbelliferous weeds. 

 X Sweet Cicely (OsmorMsa longistylis). II. Cow Parsnip (Heracleum lana- 

 tum'). III. W^lld Carrot (Daucus carota). Underneath, parenchyma cells, 

 thick-walled sclerotic parenchyma, sectional view to the right. 

 ii=nucellus. p=parenchyma. t=testa. en=endosperm. ep=epidermis. o=oll 

 duct. 



(Drawings by D. H. Pammel.) 

 36 



