172 The Ottawa Naturalist. [Jan. 



mould, thus nailing herself down inch by inch to the ground and 

 enabling the vigorous shoots at her head to get a good foot-hold 

 and stand erect some inches away from where in her day she 

 stood and flourished. 



The first step made, then, in locomotion by the individual 

 plant is by branching dichotomously, and the second is by root- 

 ing laterally as in the overweighted stems of L. lucididum. This 

 second mode of land-grabbing is an important advance on L. 

 selago and leads to the formation by a single plant of extensive 

 colonies, say a yard in diameter. At first the plant, rooted at 

 the base, grows erect for a term of years; then it begins con- 

 verting the lowest length of its stem from an upright leaf- 

 bearer to a prostrate root-bearer. The next step in the division 

 of labour is to make these successive acts of the vegetative and 

 the locomotor simultaneous. 



The beginnings of this advance are seen in L. inundatum; 

 the stem is weak and prostrate and creeps along from 2 to 4 

 inches a year by thrusting rootlets into the sand (or peat) at its 

 growing tip; in fact, it walks along by loops like a geometrid 

 caterpillar or the Walking-leaf Fern; soon after the part beyond 

 the root-anchor has found its sea legs, so to say, the brittle stem 

 severs connection ; the growing tip is cut adrift and left to steer 

 a course for itself. It is not often that you find a plant more 

 than 5 inches long and it may have 2 or 3 sets of roots on its 

 creeping stem; the stem, meantime, carries on the vegetative 

 function and is closely fringed with small leaves all along and all 

 round though those on the under side curve upwards for light 

 and air. The stems also branch laterally 3 or 4 times in their 

 few inches of length; some of these branches are weak and 

 prostrate, rooting at their tip, but one at least (usually the first) 

 is strong and erect, surmounted by a terminal fruiting spike. 



The other species which stand higher up in the scale of 

 evolution have stems that are regular runners and extend for 

 yards, sending out at intervals more or less complex systems of 

 lateral branches for vegetative and reproductive purposes. In 

 one species (L. obscurum or dendroideum) the running stem is 

 subterranean and destitute of leaves; in the other three (L. 

 annotinnni, L. clavaium and L. complanatum) they are surface- 

 runners and more or less leafy. 



Throughout this course of upward progress the Club Moss 

 may be regarded as attempting by various means to make its 

 way over the ground. From this point of view, the production of 

 a horizontal runner is the most important step in the whole line 

 of advance, since it enables the plant to throw out branches and 

 fertile shoots laterally at various points without interfering with 

 its continuous forging ahead. On this principle of classification 



