Christella sect. Leptochristella
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Notes
The plants of this group of species, small in stature and consequently simplified in structure, are difficult to characterize and need more study. They have the frond-form of Christella with lower pinnae gradually and slightly reduced (shown most notably by C. perpubescens), abundant slender acicular hairs (fewest in C. nana) and spores of the Christella type. I see no other genus to which they could be considered allied.
In Africa also are species with free veins and lacking (so far as I have observed) glandular hairs on the stalks of sporangia. For them I proposed the sectional name Pelazoneuron () but they appear to be related to a group of tropical American species in which glandular hairs of the Christella type do occur on the stalks of sporangia of at least two species () and apart from their free veins I see no clear distinction between these American species and C. hispidula. A few species in the Western Pacific (including C. harveyi in the present work) also have free veins; I suggest that they are derived from Malesian species with anastomosing veins.
In Africa also are species with free veins and lacking (so far as I have observed) glandular hairs on the stalks of sporangia. For them I proposed the sectional name Pelazoneuron () but they appear to be related to a group of tropical American species in which glandular hairs of the Christella type do occur on the stalks of sporangia of at least two species () and apart from their free veins I see no clear distinction between these American species and C. hispidula. A few species in the Western Pacific (including C. harveyi in the present work) also have free veins; I suggest that they are derived from Malesian species with anastomosing veins.