636 



BOTANY 



PAKT II 



time attached to the carpophore, which originates from the central 

 portion of the septum ; this separates from the rest of the septum and 

 bears the mericarps hanging from its upper forked end (Figs. 660-667). 



The main areas of distribution of the Umbelliferae are the steppe region of 

 Western Asia, Central North America, Chile, and Australia. 



For systematic purposes the fruits are of great importance. Each half of the 

 fruit has five ribs, beneath which the vascular bundles lie. The marginal ribs of 

 each partial fruit frequently lie close together at the septum or they may be 

 distinct ; they may resemble the three dorsal ribs or ditfer more oi' less from them. 



Fig. 6iji.—Siuin latifnHum (A iiat. sizn). Poi.soA'OUS. 



Between the five primary ribs four secondary ribs are sometimes pi'esent. Usually 

 furrows (valleculae) occur between the ridges, and beneath each furrow a large oil 

 duct (vitta) is found, extending the whole length of the fruit. On either side of 

 the carpophore a similar oil duct is present in the septum, so that each mericarp 

 has six of tliese vittae (Fig. 661). In some species additional small ducts are 

 present. The form of the fruit as seen in a cross section ditt'ers according to 

 whether the diameter is greater in tlie plane of the septum or at riglit angles to 

 this. The character of the marginal and dorsal ridges and the presence or 

 absence of secondary ridges or vittae serve to distinguish the fruits, and are 

 indispensable aids in determining the species. Since many of the fruits are 

 employed in medicine or as spices, wliile others are poisonous, their distinction 

 becomes a matter of importance. The endosperm of the seeds contains a fotty oil 

 as reserve material. 



