172 



ORGANOGRAPHY. 



generally happens that these are situated in the intervals between 

 the petioles on each side, and are hence termed interpetiolar . 



Fig. 354 



Fig. 354. A portion of the stem r, and leaf/, of the Astragalus Onobrychis. 



s. Synochreate or opposite stipule. Fig. 355. A portion of the stem r, 



and leaf/, of Houttuynla cordata. s. Axillary stipule. 



In such eases, it frequently happens that the opposing stipiiles 

 of each leaf cohere more or less completely by their outer margins, 



Fig. 356. A portion of a branch r, with two opposite leaves //, of Cepha- 

 lanthus occidentalis. s. Interpetiolar stipule. 



so as to form but one interpetiolar stipule on each side of the 

 stem {Jiff. 356), as is the case in the Cinchonas, the Coffee, and 

 other plants of the natural order to which they belong. 



Stipules, as we have already noticed, are not always present 

 in plants, but their presence or absence in any particular plant 

 is always regular, and although the appearance and arrange- 

 ment of them also vary in different plants, they are always uni- 

 form in those of the same species, and even, in some cases, 

 throughout entire natural orders, and thus they frequently 

 supply important distinctive characters in such plants and 

 orders. Thus the plants of the Cinchonacese are distinguished 

 from those of the allied order Caprifoliacese by possessing inter- 



