278 THIRD GROUP.— VASCULAR CRYPTOGAMS. 



in whorls of many members, have a radial disposition of their branches. The gemmae 

 common in L. Selago are according to Hegelmaier branches of a peculiar kind. 



These gemmae, which have a few leaves and a rudimentary root and eventually 

 become detached, are formed on the shoot in place of a leaf. In other species Stras- 

 burger found adventitious buds at the base of the stem, as in Z. alo'ifolium, L. reflexuni 

 and others. As the leaves stand from the first close above and beside one another so 

 as to cover the surface of the stem, there are not only no internodes in the 

 Lycopodiaceae any more than in Ophtoglosstim, Marattia, Aspidiuvi and Isoetes, but 

 the outer layer of the cortex of the stem is genetically connected with the tissue of 

 the bases of the leaves ; it is not till intercalary growth s-ipervenes at a later time that 

 the leaves move farther apart, and a line of demarcation often very distinct arises 

 between the base of the leaf and the stem. 



The rudiments of the leaves in the Lycopodieae appear on the vegetative cone as 

 pluricellular protuberances of considerable breadth ; growth is at first at the apex, 

 but this in most cases soon ends in a hair-like prolongation, while intercalary growth 

 begins and proceeds towards the base. The size and shape of the leaves varies much 

 from one species to another ; but they are always simple, unbranched, without a stalk 

 and sessile with a narrow base ; they are sometimes closely applied to the stem up to 

 the free point, like the leaves of Thuja, but more commonly they are free along their 

 whole length, and acicular or narrow ; there is a mid-rib only and no lateral veins as 

 in all the Lycopodineae. 



Tht phyllotaxts is sometimes verlicillate, sometimes spiral, or both on the same 

 plant. The whorls may consist of decussate pairs, or be of three, four, or many 

 members, and in creeping stems are usually inserted on a transverse zone which is 

 oblique to the axis of the stem. The number of members in the whorls varies in the 

 same shoot. According to Hegelmaier the whorls are true whorls, that is, the leaves arise 

 simultaneously at the same level on the growing point, but the spiral arrangements are 

 also spiral from the first, and the divergences undergo no subsequent displacements of 

 any importance. The small and at the same time highly variable divergences of the 

 leaves are remarkable, as Braun has observed ; he found in L. clavatum with spiral 

 arrangement the divergences f , t\, j%, i\, /^, and whorls of from four to eight 

 members ; in annoiinum the divergences f , f , and whorls of from four to five members ; 

 in Z. inundaium a divergence of % and whorls of five members, and so on ', 



The roots in the primary stems of the creeping or climbing Lycopodiaceae arise 

 singly, and when they penetrate into the ground they bifurcate in crossing planes. 



It has already been mentioned that in erect stems, as in Z. Selago, L. Phlegmaria, 

 and Z. aloifolium, all the roots emerge in a tuft from the base of the enlarged tuberous 

 stem ; but these roots have their origin much higher up the stem, according to 

 Strasburger as much as five centimetres above the base of the stem and even above 

 the first bifurcation ; they come, it will be understood, from the periphery of the axile 

 vascular mass, but are peculiar in growing downwards inside the fundamental tissue 

 of the stem, and occasionally even dichotomise in it (see Angiopteris, p. 253). 



The sporangia of the genus Lycopodium are formed singly on the base of the 

 leaves. They are considerably larger than in the Ferns, as is the case in all the 



Bot. Ztg. 1872, p. 



