HOLE : SOME INDIAN GRASSES AND THEIR CECOLOGY. 59 



The results regarding this point which have been obtained, however, up to date can only 

 be regarded as approximations for the following reasons : — 



(1) The correct total annual period of vigorous growth for the majority of the culms 



of a species in a particular locality can only be determined by observations 

 extending over several years, as this period fluctuates to some extent with the 

 seasons. 



(2) The period required for the individual development of leaves and internodes 



also depends to some extent on the character of the season and a correct 

 average can only be obtained from observations extending over several years. 

 Thus in years when the rains stop abruptly and the soil dries rapidly, the 

 normal period of development of certain internodes would be cut short. 



As opportunity permits observations are now being made at Dehra Dun with the object 

 of determining more precisely than has been possible up to date the correct average period 

 of vigorous growth for each species in selected localities and the data thus obtained will 

 indicate how far the approximation which has been provisionally adopted as correct can 

 be relied on. 



An average flowering culm of the form of this species usually seen in wet pastures 

 and agricultural lands shows about 9 (7 — 12) very short internodes at the base aggregating 

 about an inch in length and then 11 long internodes excluding the terminal segment which 

 terminates in the panicle. The leaves on the basal six short internodes have no green 

 lamina, which gives 14 internodes with green leaves and indicates a period of 14 months' 

 vegetative activity for the production of the culm, which may therefore be described as 

 annual. This form flowers in August — September. The most vigorous growth takes 

 place in the rains from June — September, but there is no marked season of rest and vege- 

 tative activity proceeds more or less throughout the year, at all events in the locality now 

 dealt with. The average culm therefore would start its devlopment at the beginning of 

 the rains in July and complete its cycle of 14 months at the end of August or beginning of 

 September. 



The xerophilous form of the species common on dry sand has a slightly shorter period 

 of vegetative activity. Flowering takes place in August and the young culms commence 

 their development chiefly towards the close of the rains in August — September. 



The average number of internodes bearing green leaves on the culms examined of this 

 form is 12, thus indicating a period of 12 months' vegetative activity. 



The flowering culms either die back to the ground after flowering, or their basal inter- 

 nodes persist and in the latter case secondary culms are usually developed from their 

 nodes. 



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