io6 THE PLANT WORLD. 



armed with thorns than the Cat-brier, though in this respect the 

 larger vines of 5. glauca are by no means to be despised. While the 

 Cat-brier's stem is a dull green and rather harsh to the touch, that of 

 S. glauca is of exquisite smoothness and pleasant to feel, and more 

 or less covered with the delicate bloom which gives to the plant its 

 specific name. The color of the stem in these winter days is generally 

 a limpid purple or wine-color, blotched and speckled with green. 

 Seen under the lens, it reminds one of the gorgeous back of some 

 tropical snake. The same exquisite coloring will be found also on 

 the peduncles and pedicels of the black fruit which is still clinging to 

 some of the vines in mid-winter. Even the prickles are beautiful in 

 hue, being a clear chestnut-brown, quite distinct from the dead green 

 or yellow-white of the Cat-brier's thorns. 



Taken altogether, S glauca is by no means the least among the 

 many interesting sights in the fields and woodlands of winter, and 

 any one who loves the plants, will be well repaid by a trip at this sea- 

 son to examine it in the field. 



Philadelphia. 



PROTECTIVE STIPULES. 

 By Charles A White. 



THERE have been many discussions among botanists as to the 

 true nature of stipules, among the latest and best of which are 

 those by Dr. A. A. Tyler and Prof. Lester F. Ward. It is 

 not my purpose to join in those discussions, but only to point 

 out the important protective use which two well known plants, Rheum 

 and Smilax, respectively make of their stipules. 



One of the first of the perennial plants of the kitchen garden to 

 make its appearance above ground in the spring is Rheum (the Pie- 

 plant). While other plants are hesitating in fear of frost. Rheum, if 

 she has, during the previous seasons, established a vigorous main 

 stem, boldly thrusts up her night-capped head to reconnoitre. Per- 

 ceiving no immediate danger she rises a little further, throws oflE her 

 head-wrap and begins to display that cluster of flower buds which 

 springs from the axil of her first leaf, and also to slowly evolve the 

 leaf itself. 



This leaf, although the first to appear, is the lower-most one of 

 those which are to adorn the coming stem when it shall have reached 

 its full height ; and the head-wrap which she has just cast aside was a 

 perfectly closed membranous sac, made of the stipules of that leaf by 

 being neatly and completely joined together at their edges. The 



