A morphological assessment ofAdiantum hispidulumSwartz andA. pubescensSchkuhr (Adiantaceae: Filicales) in New Zealand

Abstract

Two polymorphic members of the Adiantum hispidulum Swartz complex, A. hispidulum sensu stricto and A. pubescens Schkuhr, have been critically studied on a morphological basis, utilising frond and hair forms, pinnule shape and size, soral features, number of sporangia per sorus, sporangial size, annulus position and number of indurated cells, spore shape and size, rhizome and stipe paleae. Separation of the two taxa is traditionally based on frond form (A. hispidulum being described as pinnate and A. pubescens as pedate), and indumentum characteristics (A. hispiqulum having medium to short stiff hairs, A. pubescens having long lax hairs). This study shows that only those characters associated with the pinnule hairs can be used to consistently separate the two taxa (A. hispidulum has short (63-815 /lm), stiff, often pigmented hairs with enlarged basal cells, while A. pubescens has long (251-1003 /lm), soft, pale hairs with narrow basal cells). However, even these characters showed a high degree of variability. Adiantum pubescens is given varietal status as A. hispidulum var pubescens.

Taxonomy and spore morphology of genus Adiantum (Vittarioideae; Pteridaceae) from Pakistan

“…The spore morphology of Adiantum species observed under SEM represents variations in size, shape, aperture, exospore thickness, and surface ornamentation, as described in many previous studies (Dai, Wang, & Yu, 2005; Kovalska, 2013; Large & Braggins, 1985, 1991, 1993; Prado & Hirai, 2013; Tryon & Lugardon, 1991, 2012). The spores of Adiantum taxa are usually trilete and triangular in proximal and distal view, spheroidal, ellipsoidal, hemicircular in equatorial view; spore surface is often cristate, globose, reticulate, and tuberculate (Jiaxi, 1997; Nayar & Devi, 1967; Schuettpelz, Davila, Prado, Hirai, & Yatskievych, 2014; Wang et al, 2017).…”

Molecular Phylogeny of Maidenhair Fern Genus Adiantum (Pteridaceae) From Lesser Sunda Islands Indonesia Based on RBCL and TRNL-F

“…Adiantum hispidulum is distributed in southern India, eastern Africa and the Pacific Islands (Hoshizaki & Moran, 2002) and also found in New Zealand (Large & Braggins, 1993), Australia (Bostock et al, 1998), Thailand (Boonkerd & Pollawatn, 2013), Indonesia (Posthumus, 1944;Lu et al, 2012) and China (Lu et al, 2012). The cpDNA variation observed in Adiantum hispidulum s.l.…”

“…Adiantum hispidulum has been considered to be a polymorphic species, due to the variation at several morphological characters. Large and Braggins (1993) described two polymorphic members of the New Zealand A. hispidulum complex, A. hispidulum s.s. and A. pubescens Schkuhr., which distinguished based on their pinnule hairs. One subgroup with short (63-815 µm), stiff, often pigmented hairs with enlarged basal cells was treated as A. hispidulum var.…”

“…Six species occur in Fiji (Brownsey & Perrie, 2011). Seven species are found in New Zealand (three of them are endemic) (Large & Braggins, 1993;Bouma, 2008). About 60 species are native to Asia (Lu et al, 2012).…”

Sporangium Exposure and Spore Release in the Peruvian Maidenhair Fern (Adiantum peruvianum, Pteridaceae)

“…These so-called false indusia are a few millimeters long and are supplied by several parallel veinlets (cf. [ 13 , 14 ]). True indusia, in contrast, are epidermal outgrowths that do not appear in A .…”