UMBELLIFERJE. 



141 



HydrrcoUjIc asiatica. 



same point (fig. 157) terminate each in a small umbel (or false 

 umbel ^) simple or with two or several ranks of flowers superposed, or 

 in a compound umbel. ^ This is most generally the case in the true 

 Hifdrocotifk,^ which have pointed valvate petals, and fruit with no or 

 very indistinct secondary ridges. In Centella, 

 another subgenus of which a separate genus has 

 been formed, the petals are obtuse, wider, oftener 

 imbricate. The secondary ridges of the fruit are 

 frequently more distinct. In H. asiatica (fig. 

 158-161), which may be considered a type of this 



group, the floral pe- 

 Eydrocotyie asiatica. duucles bear ouly a few 



flowers, often three, of 



which one, older, is 



terminal, accompanied 



by two bracts in the 



axil of each of which 



is a flower of the second 



generation. It appears 



then a biparous and 

 Fig. 160. Fruit (f). three-flowered cyme.^ 



In Micropleura,^ which 

 we make another subgenus, the inflorescences, 

 more or less ramified, bear fertile terminal flowers, 

 and, immediately below, a few younger flowers, 

 mostly sterile, male and pedicellate. 



Thus constituted,® the genus Hydrocotyle comprises about seventy 

 species,^ mostly aquatic, which belong to all the warm and temperate 

 regions of the globe. 



Fig. 161. Trans, sect, 

 of fruit Cf). 



^ The central flower is often older than those 

 which immediately surround it. 



2 Particularly in II. bonar'iensis, where not 

 only a common axis terminates in an umbel (P) 

 of small secondary floral groups, but where the 

 pedicels of the umbellules are accompanied by 

 a variable number of solitary flowers inserted 

 at the point of divergence. 



^ Euhydrocotyle'DQ. Prodr. sect. 1. 



* Apart from development, it might be con- 

 sidered either a terminal cluster or a biparous 



cyme, in either case three-flowered, but without 

 possible distinction. 



5 Lag. Oe. JEsp. Emigr. 15.— DC. Mem, 71 ; 

 Prodr. iv. 71.— Endl. Gen. n. 4360.— B. H. Gen. 

 873, n. 2. 



6 Sect. 3 : 1. Euhydrocotyle (DC.) ; 2. Cen- 

 tella (L.) ; 3. Micropleura (Lag.). 



? R. et Pav. PL Per. t. 245-248.— Cav. Icon. 

 t. 488, fig. 1.— Wight, Icon. t. 564, 565, 1002, 

 1003.— Link et Ott. Ic. PI. Bar. t. 21.— Hook. 

 Icon. t. 303, 312 ; Exot. Fl. t. 29, 30.— Reichb. 



