Author: Chang Yu-lung
J Integr Plant Biol 1963, 11 (1): -.
The spore morphology of 20 species of Loxogramme Presl has been studied. The following
conclusions may be drawn from the present investigation: 1. In Loxogramme there are two
predominating spore types, the trilete and the monolete. 11 species of the material studied belong
to the former, and 9 other species to the latter. The trilete spore is circular, subcircular or round
triangular in polar view, and ellipsoidal in equatorial view. The polar axis ranges from 26 μ to 65
μ, and the equatorial axis from 33.8 μ to 80.6 μ. The monolete spore is long ellipsoidal or
ellipsoidal in polar view, and bean-shaped in equatorial view. The polar axis tangs from 26 μ to
62.4 μ, and the equatorial axis rangs from 40.3 μ to 94.4 μ. The structure of exine of all
species studied in this genus is fairly uniform. The outline of spore is slightly undulate or crenate.
The exine, about 1.3–3.9μ in thickness and ornamented with small, irregularly shaped
verrucae, is usually two-layered, but sometimes its stratification is indistinct. 2. According to the
two predominating spore types in Loxogramme, we may divide this genus into two groups: the one
belongs to trilete spore, and the other to monolete spore. 3. A few monolete spores were found
among the predominating trilete spores of L. assimilis Ching and L. grammitoides (Bak.) C. Chr.,
while a few trilete spres were found also among the predominating monolete spores of L. parallela
Copel, Some spores with varying fissures were observed as well in these three species.
According to the degree of variation, two possible “transitional ways” from the trilete type to
the monolete type are here suggested. These facts as mentioned above may be significant to the
toxonomy of Loxogramma, and may indicate that the trilete type and monolete type are related each
other in the evolution of ferns. 4. According to the morphology and anatomy in Loxogramme,
Prof. R. C. Ching (1940) separated Loxogramme from Polypodiaceae as a new family，
Loxogrammaceae. It has been known that only one spore type i.e. the monolete type is found
in Polypodiaceae, while in Loxogramme both the monolete and trilete types are found. It is
generally accepted that the trilete is the primitive type, and the monolete is more
advanced type. Thus Loxogramme occupies a phylogenetical position more primitive than
Polypodiaceae. We agree with Prof. R. C. Ching's viewpoint. 5. The morphology of trilete spore
of Loxogramme is very similar to Grammitis Sw. However, Loxogramme is more advanced than
the latter from the point of view of palynology, because the monolete type is, as mentioned above,
also found in Loxogramme. Thus Loxogramme may be derived from Grammitis as E. B.
Copeland (1948) pointed out. It must be noticed, however, that Copeland (1948) put Grammitis
in Polypodiaceae, and therefore actually he recognized Loxogramme as a member of Polypodiaceae.
R. C. Ching (1940) first separated Grammitis from Polypodiaceae as a new family of Grammitaceae,
and only later did Copeland (1951) accept Ching's viewpoint. From the point of view of palynology,
it seems that the taxonomic and phylogenetical position of Loxogramme is more closely related
to Grammitaceae than to Polypodiaceae.