58 Journal of the Asiatic Society of Bengal. [February, 1914. 



Botanical description of the plant, as found on the Madias 

 Coast — special attention being paid to the leaf. 



Zoysia pungens, Willd., is a small much-branched rigid gla- 

 brous grass with a very long, slender, wiry, creeping root-stock 

 usually 2 to 3 ft. long, occasionally even 5 ft. long, with 

 interlaced branches, giving off at definite intervals, short., stiff, 

 leafy stems 4 to 8 in. high above the ground, and long thin 

 filiform roots usually nearly a foot long below the ground. 

 Leaves f-l| in. long, spreading dorsally rounded, margins, 

 strongly incurved, subulate, pungent, glaucous-green, quite 

 smooth. Sheath very short. Ligule a very narrow, abun- 

 dantly ciliolate membrane. Racemes 1-1 J in. long, strict, erect. 

 Spikelets red brown, shining T ^th in. long, erect. 



In order to find out what exactly are the structural adap- 

 tations found in the leaf of Zoysia pungens on account of its 

 curious habitat, let us roughly examine the actual state of the 

 surrounding environment under which it has to maintain suc- 

 cessfully its survival in the struggle for existence. It will be 

 convenient to consider the nature of the surroundings under 

 the following heads: 



Soil. — It is a matter of common knowledge that the soil 

 near the sea is sandy, dry and poor in humus. The subsoil may, 

 of course, be permeable and may also admit of being thoroughly 

 soaked to some depth at each fall of rain, but unfortunately 

 dries very quickly when the rain is over. In addition to this, 

 the soil of these sandy regions contain always an excess of 

 mineral salts derived from the sea in spray or by percolation. 

 These two factors, viz. scarcity of water in the soil and excess 

 of mineral salts in it, are quite enough to reduce considerably 

 the absorption of water by the roots. In fact, they render 

 absorption of water and food-material by osmosis extremely 

 difficult, How exactly then can our plant flourish in such 

 a place? It is clear that it must have armed itself with 

 certain devices, whereby it remains satisfied with the limited 

 supply of water and also counteracts the injurious influence 

 of the concentrated mineral solutions in the soil, managing 

 at the same time to take in its necessary food. 



Temperature. —The influence of temperature on plants has 

 been recognized as a very important one from early days. 

 Every plant can live only at temperatures lying between two 

 extreme degrees which are termed respectively its maximum 

 and minimum points. The over-stepping of either of these 

 limits sooner or later results in the death of the plant. But 

 these two points vary for different species and even for different 

 functions. Consequently, it is not possible to give any abso- 

 lute figures for maximum and minimum points. However, 

 we may say approximately that the average points of minimum, 

 optimum and maximum temperatures in the case of meta- 

 bolism of plants are about 10 C ; 30 C and 50°C respectively. 



