filicineje: 433 



The Formation of Adventitious Buds'^ which do not result from the terminal 

 branching of the stem, is, in Ferns, connected with the leaves. These buds make 

 their appearance on the leaf-stalk or on the lamina itself. The shoots of Pteris 

 aquilina which spring from the leaf-stalk (Fig. 301) stand at the back of the 

 individual leaf-stalks near the base; in Aspidium Filix-mas (Fig. 302) they arise 

 at a moderate height above the insertion, usually on one of the lateral edges of the 

 leaf-stalk. In both cases Hofmeister states that they are formed on the young 

 leaf-stalk even before the first appearance of its lamina, and before the differentiation 

 of its tissue. A single superficial cell of the leaf-stalk is the mother-cell of the new 

 shoot; and as the surrounding tissue of the leaf-stalk grows like a wall around them, 

 they may, as in Pteris, be placed in a deep depression, where they sometimes remain 

 dormant for a long period. Even when the leaf has long died away, the leaf-stalk 

 still remains succulent up to the bud, and filled with food-materials; and in 

 Aspidium Filix-mas vigorous stems are not unfrequently found with a number of 

 leaves at their posterior end still attached to the leaf-stalk of an older stem. In 

 some cases, as in Struthiopteris germanica, the buds produced on the leaf-stalks 

 develope into long underground stolons furnished with scale-leaves, which become 

 erect at the end and unfold a crown of foliage-leaves above ground. In Nephro- 

 lepis undulata they swell at the end into tubers. Adventitious buds spring from the 

 lamina, especially in many species of Asplenium ; in A. furcatum^ e.g., often in large 

 numbers from the middle of the upper surface of the pinnae; in A. decussatum from 

 the base of the pinnae (or axillary on the mid-rib?). Ceratopteris thalictroides not unfre- 

 quently produces buds in the axils of all the divisions of the leaves, which, especially 

 when the detached leaf is laid upon damp ground, develope rapidly, and grow into 

 vigorous plants. According to Hofmeister, these buds also spring from superficial 

 cells of the leaf. The long pendulous leaves of some Ferns touch the ground with 

 their apices, root, and sometimes also put out new shoots from these points {e.g. 

 Chrysodium flagelliferum, Woodivardia radicans, &c.). 



The Roots. During its growth the stem is usually constantly forming new roots 

 in acropetal succession, which, in the creeping species, become at once fixed to the 

 substratum. [As a rule they are developed quite endogenously, but in Ceratopteris 

 thalictroides, according to Kny, they arise from cells immediately beneath the 

 epidermis. According to Conwentz, a distinct relation can usually be observed 

 between the number of the roots and that of the leaves.] In Pteris aquilina the 

 new roots appear close behind the apex, and, both in this species and in Aspidium 

 Filix-mas, they also proceed from the adventitious buds of the leaf-stalk while 

 still very young. It has already been mentioned that, in the last-named species, 

 when the mature stem is completely covered by leaf-stalks, all the roots spring 

 from them and not from the stem. In Tree-ferns especially the lower part of 

 the erect stem is entirely covered by slender roots, which grow downwards, forming 

 an envelope several inches thick before they penetrate the soil, and thus give a 



both in reference to the formation of leaves and to the terminal branching of the stem. [According 



I to Sadebeck, the pinnse are developed as lateral outgrowths, but the branching of the veins is the 

 result of the dichotomy of the marginal cells ; see supra.'] 

 ^ [On the development of these adventitious buds, see Heiniicher, Sitzber. d. Wien. Akad. 1878 

 and 1881.] 



