FLORA OF CUTCn. 160 



tTliimluhir hairs : nlso the petals are o;hiii(liil;u-piihescent as well 

 as the capsules. Those glands secrete an ethereal oil which 

 resembles very much that of the rue. It is just the vapours 

 .)t' that oil which acts protective against too profuse transpiration ; for 

 it is a well known tact that air ]a<lcn with vapours of an ethereal oil 

 is much less permeable to radiating heat than ])ure air. In this way 

 a plant, surrounded liy a layer of vajiours of an ethereal oil, will be 

 protected at (hiy-time against cverheating and consequently against 

 excessive trans]iiratit)n, and at night against too great a cooling down. 



The ^tem- and liranclies of (runandropus penfaphf/Ua are covered 

 with white sjireading hairs and the leaves are pubescent on both 

 sides, whilst the sepal< and the ovary are clothed with glandular 

 hairs. 



The young stems and branches, including the leaves of ('apparis 

 spinosa are covered with a grayish-white layer of wax which just allows 

 the green colour to be slightly yisible. This contrivance greatly 

 reduces cuticular transpiration. The same effect is produced by the 

 orange colour of the stipules, which in this plant assume the form of 

 two hooked thorns. 



The reduction of the transpiring surface is well shown in Capparh 

 aphjlla. The older branches are quite destitute of leaves, and the 

 younger shoots bear exceedingly small and spinous-pointed leaves. 

 Also in this case, the stipular thorns are not green, but orange-yellow. 

 The voung parts of Cap par is horrida are protected by a rufous tomen- 

 tnm. Poli/gala e7'iojytera has narrow linear leaves, whilst specimens 

 of the same species, iiut growing in less dry parts of the 

 Presidency have usually oblong-ovate leaves. In Polycarpcea corr/m- 

 hoKa the young branches and the pedicels are hoary-pubescent, the 

 leaves narrow linear. The species of Fortulaca are ])rotected in 

 various ways : The stems of P. oleracea are reddish, the leaves 

 fleshy with reddish margins. We find fleshy leaves also in Por- 

 Julaca ijuadrifida and F. tuherosa : the stipules form a ring 

 of silvery hairs in the former, and a ring of brownish ones in 

 the latter. 



Tamarix dioica and ericoidex have got minute scale-like leaves. 



Both make use of the hygro copic salts that collect on^the surface of 



the plant. At times of dr night they absorb the moisture which is 



<-ontain<?d in the atmosphere in the form of vapours. Thus it happens 



2" 



