300 Mr. Alfred Barton Rendle [May 17, 



WEEKLY EVENING MEETING, 



Friday, May 17, 1918. 



Sir William Phipson Beale, Bart., K.C. M.P., Vice-President, 



in the Chair. 



Alfred Barton Rexdle, M.A. D.Sc. F.R.S. 



The Story of a Grass. 



The grasses form one of the largest and most widespread families of 

 flowering plants ; they are adapted to very different conditions of 

 soil and climate, but have a remarkably uniform plan of structure. 

 Wherever conditions allow of plant-hfe on land, there, almost without 

 exception, the family is represented. In the aggregation of many 

 individuals of one and the same, or a few species, either growing 

 alone or densely scattered through a mixed herbage, covering large 

 areas, it form^ a pre-eminent type of the earth's vegetation ; as, for 

 instance, in the grass-carpets forming the meadows and pastures of 

 temperate or cold climates, or the coarser growth of steppe or prairie 

 vegetation. These sociable grasses are of importance in that they 

 protect the soil from too great evaporation of water, keeping it warm 

 and moist, and covering other plants in the resting stage during cold 

 or dry seasons. The penetrating effect of their roots and creeping 

 stems helps to break up a stiff soil. 



The Reed-grasses invade fresh-water lakes, pools and streams, and 

 even sea-inlets ; the remarkable spread in recent years of a hybrid, 

 Spartina Toinisendi^ on various parts of the South Coast supplies an 

 interesting example in land-reclamation. Other species are character- 

 istic of sand-dunes, where their long penetrating underground stems 

 serve as sand-builders, and are hence of great economic importance. 

 Our cereals are grasses, though owing to long cultivation their wild 

 progenitors are often unknown or uncertain ; Sugar-cane is also 

 a grass. Bamboos are large grasses with a woody, generally much- 

 branched stem, often attaining tree-like proportions. 



The general plan of structure of a grass, as seen in one of 

 our common species, shows a fibrous root ; a stem leafy at the base, 

 and in annual species lengthening only to bear the flowers ; the 

 nodes and internodes of the stem or culm ; the sheath ing-leaves 

 arranged right and left in two rows ; and the numerous flowers carried 

 up at the end of the stem. Branches are developed from the lowest 

 nodes ; branching from the upper nodes is rare in grasses of the 



