DIFFERENT ORIGIN OF EQUIVALENT MEMBERS. 
^75 
the Hepaticae Radula and Lejeunia ; the branch springs (as shown in Fig. ii6, p. 153) 
out of the lower part of a segment of the stem, the upper part of which has developed 
into a leaf. In Fontinalis this occurs below the median line of the leaf, in Sphagnum 
laterally below one half. According to the same observer, the lateral branches arise 
in place of a half-leaf beside the remaining half in many Jungermanniese, as Frullania^ 
Madotheca, Mastigobryum, Jungermannia trichophylla ^. If each tooth in the leaf-sheath 
of an Equisetum be considered as a leaf, the buds originate at the side of the leaves and 
between them, for they break through the leaf-sheaths between the teeth. In Gharacea; 
and Angiosperms the normal lateral branchlets spring from the acute angle which the 
leaf forms with the stem (Figs. 129, 131). Usually only one is formed above the middle 
of the insertion of the leaf, or two or three one above another; sometimes several 
are formed side by side, as in the bulbs of Muscari (Fig. 130), and the flowers in the 
axils of the bracts of Musa. Such branchlets are called Jxillary Shoots; in Angio- 
sperms the branching is, with a few doubtful exceptions, always axillary'^. 
The axillary shoot is usually so situated that it is attached both to the Subtending leaf 
in the axil of which it grows and to the primary axis, and is therefore in direct con- 
FiG. 131. — Apical region of a primary axis 
oi Dictamnics Fraxinella, seen from above; 
J apex of the primary axis ; b b b the young 
leaves ; k k their axillary buds, the two young- 
est leaves have not yet axillary buds. 
FIG. 132.— Young inflorescence of Isatis 
taicrtca, seen from above ; s apex of the 
axis of the inflorescence ; the flower buds 
appear beneath it (in whorls of four) ; the 
youngest are still simple leafless elevations. 
nection with both. But it is not unusual for the lateral shoot to advance along the 
primary axis and thus lose its connection with the subtending leaf ^, or contrariwise to 
appear as if attached to the base of the leaf away from the axis. Examples of both are 
furnished by the sporangia of Lycopodium and Selag'mella. The advance of the axillary 
shoot along the base of the subtending leaf is not uncommon in the inflorescence of 
Phanerogams, where the flower-bud springs from the base of the bract, as in HippuHs 
(Fig. 119, p. 155), Amorpha, Salix nigricans, Sedum Fabaria, &c. But, on the other 
hand, the subtending leaf may advance on its axillary shoot, when it originates later than 
Akad. der Wissen, zu Wien, vol. LVII, 1868, and vol. LIX, 1869 ; and Bot. Zeitg. 1 871, no. 34. See 
also more in detail, Book II, Muscinese. 
^ Leitgeb, Bot. Zeitg. 1871, p. 563 ; see also Book II, Hepaticae. 
^ [The relationship of leaf and lateral shoot is intelligible in the Muscmeas, where the two struc- 
tures are derived from the same ultimate segment of the apical cell. In Phanerogams Warming 
considers (/. c. p. xxiii) the leaf and its axillary bud (which are always united at their base) to no 
less form a whole, and to constitute a double organ whose parts have a different morphological 
value and are sometimes equally developed, while in some cases one is developed at the expense of 
the other.] 
^ [This occurs not unfrequently in the flowering shoots or inflorescences of Phanerogams, when 
such shoots are termed extra-axillary. '\ 
