Pteridophytes . Are they vestigial? 235 
are found also in the axils of large ‘ foliage leaves ’ below. This was 
verified also in other specimens. 
61. L. subulatum , Desv. The condition here is the converse of 
Z. varium. The strobili are well defined, their leaves being broad 
and ovate, while the foliage leaves are lanceolate-acuminate : but 
the lower part of the strobilus with leaves of the sporophyll-type 
may have no sporangia, and higher up irregular zones may also 
be sterile : the apex of the strobilus may revert to the vegetative type 
of leaf. 
62. Z . ophioglossoides, Lam. (inch L. fertile > Baker), shows transi- 
tions of the fertile strobilus to the sterile state. 
63. Z. pinifolium, Blume, ditto. 
67. Z, Phlegmaria , L. There is a sharp contrast between the 
large foliage leaves and the small sporophylls, and the transition is 
usually sudden, though intermediate leaf-types do occur. Usually 
the strobili are continuously fertile, but at the branchings the first 
leaves above may be sterile, though of the small sporophyll-type. 
Transitions from the fertile to the sterile type of shoot, and back to 
the fertile, are not uncommon. 
It is seen from the above notes that though in the Phleg - 
maria-group^ which are epiphytic, the spikes are ‘ slender, 
dichotomously forked, with bracts very different from the 
leaves V isolated sporangia pay be found in the vegetative 
region (Z. varium ), and there may occasionally be alternating 
sterile and fertile zones (Z. nummularifolium :), while leaves of 
the sporophyll type may develop no sporangia (Z. subulatum , 
Phlegmaria). Transitions from the fertile strobilus to the 
larger leaved foliage shoot are frequent (Z. nummularifolium , 
subulatum , ophioglossoides , pinifolium , Phlegmaria). Thus 
the differentiation of the strobilus is one of external form, 
rather than a rigid difference of intimate character. The con- 
verse conditions of Z. varium and Z. siibulatum show that 
the difference in size of sporophylls and foliage leaves is not 
due directly to correlation in the individual : other cases 
might be quoted supporting the same conclusion, notably 
Z. serratum. 
Baker, loc. cit., p. 8. 
