THE DOG'S MERCURY. 



J AS. E. McDonald. 



Though not looked upon with very much favour by lovers of 

 wild flowers in general, the Dog's Mercury (Mcvcuvialis perennis) 

 offers nianv points of interest in its life history. Its habit of 

 boring through the soil in early winter giving promise, by its 

 greener}', of the balmier days of spring, and here and there 

 opening a few of its inconspicuous, but none the less welcome 

 flowers earh' in January,"^ suffice in themselves to make it 

 worthy of notice. 



As herbaceous plants go, it may be considered almost ever- 

 gi-een : by the time the stems of one year have departed some of 

 those for the succeeding year will have already emerged from 

 the soil, and though the leaves are yet unfolded, the flower 

 buds are e\ddent sometimes as early as October. 



Like the Stinging Nettle, the Butterbur and some other 

 dioecious perennial herbaceous plants, the Dog's Mercury grows 

 in clumps or ' colonies ' of one sex, though usually a colony of 

 the opposite sex occurs in the near vicinity. This feature in 

 €ach case may be explained as follows : — A seed on finding a 

 suitable place, germinates, and in the course of time arrives at 

 maturity. Both before and after this stage, branches are given 

 off below ground, which spread in various directions, sending 

 up shoots to the surface at intervals. Each seed furnishes a 

 plant of one sex only, hence a colony of the same sex is formed. 



The course of development of the Dog's Mercury from seed 

 to maturity is as follows : — During July, when the capsules 

 on the female plants are ripe, the seeds are discharged with 

 some force. After reaching a suitable place — hedges or thickets 

 — a period of apparent rest of several months ensues. During 

 this time the hard shell (testa) protects the enclosed plantlet 

 and its food (endosperm). 



Germination takes place sometimes in October and some- 

 times in the February following. Usually the seed leaves 

 (cotyledons) remain face to face within the hard shell below 

 ground (hypogeai) for some time at least, even after absorbing 

 the endosperm and the plumule has emerged from the soil. 



* In a certain slieltered woodland near Stockport the writer ha*? 

 gathered specimens, several years in succession, of both staminate and 

 pistillate forms with some flowers open the first week in January. 



Naturalist, 



