Holttum (1978) recognized two subgroups in Lomariopsis based on the sequence of successive juvenile leaves, what is known as a heteroblastic leaf series. In one group, the Sorbifolia group (Moran, 2000), the leaves become pinnate when 2-3 cm long, whereas the Japurensis group does not become pinnate until over 15 cm long. The two groups are supported on the basis of DNA (see phylogenetic tree ) and spores .
Successive juvenile leaf development (heteroblastic series) in Lomariopsis. A. Sorbifolia group. B. Japurensis group. (Modified from Moran, 2000.)
Pinnate juvenile leaves of typical of the Sorbifolia group, as shown by Lomariopsis vestita from Costa Rica. (Photo R. Moran)
Simple and entire juvenile leaves typical of the Japurensis group, as shown by L. latipinna from Ecuador. (Photo R. Moran)