Hemionitis takeuchii (W.H.Wagner) Christenh.

Yesilyurt, J. (2005). The Fern Genus Doryopteris (Cheilanthoideae-Pteridaceae) in the Hawaiian Islands. Kew Bulletin, 60(4), 547-558. Retrieved from http://www.jstor.org/stable/25070241

Type

Oahu. Diamond Head, open slopes near tunnel, 100 - 120 m, 22 March 1988, W Takeuchi 3824 (holotype MICH).

Morphology General Habit

Rhizome sub-erect, scales lanceolate, with sporadically dentate margin

Morphology Leaves Petiole

Petiole with c. 1 mm diam., winged, brown, glabrescent

Morphology Leaves

Fertile and sterile fronds moderately thin to sub-coriaceous, venation partially (with at least two rows of areoles along the midrib) to almost completely anastomosed on both fronds, lamina glabrous Fertile and sterile fronds dimorphic. Sterile fronds up to 10 cm long, lamina up to 5 cm long, pentagonal to oval, usually pinnate at base or pedate-pinnatifid; fertile fronds up to 17 cm long, lamina up to 8 cm long, ovate to elliptical, pedately divided, pedate-pinnate-bi-tripinnatifid to pinnate-1 - (2)-pinnatifid, lamina with lanceolate apex

Morphology Leaves Pinnae

Pinnae/segments ascending, falcate to lanceolate, opposite, with 3-5 pairs, first pair of pinnae/segment adnate to sub-sessile, rachis length between first pair of pinna and second usually twice than between second and third pair, canaliculate; basal pinnae/segments longer than the second pair, asymmetric, first lobes/segments at base of pinna/segments usually smaller on acroscopic side and longer on basiscopic side, rest usually same size with some lobes parallel and some not parallel-sided, varying from long-ovate, lanceolate to linear lanceolate, entire to crenate, with obtuse to long cuneate apices

Morphology Reproductive morphology Sori

Marginal sorus in a vascular commissure, broken at the sinus region and notch; sterile tips of the lobes/segments short, receptacle and indusium continuous, indusium with entire margin

Morphology Reproductive morphology Sporangia

Sporangium moderate short to long-stalked; annulus with c. 18 cells.

Distribution

Oahu and Lanai.

Note

Doryopteris takeuchii can be confused with D. decipiens when the specimens bear only fertile fronds, but differs in being clearly pinnate at the base of the lamina, lobes/segments with crenate margin and indusium with entire margin. Sterile fronds resemble D. decora and D. tryonii. This apparent hybrid origin has the pinnate condition of the lamina and the variable states of the segments (from lanceolate to filiform) as its main differences. When Wagner (in Wagner et al. 1999) described D. takeuchii he did not mention the possibility of its hybrid origin. However, the intermediacy of the several morphological characters observed in specimens identified as D. takeuchii are possibly the result of hybridisation between D. decipiens (e.g. lamina dissection, pinnae/segments outline) and (most probably) with D. decora (e.g. pinnate condition, segments linear-lanceolate).

Another possible parent could be D. subdecipiens (e.g. apex of the ultimate segments/lobes; lamina glabrous), although it is also a species with suspected hybrid origin, which seems to be well established. D. takeuchii should be examined in cytological or allonzyme studies. Wagner et al. (1999) gave its distribution as Diamond Head Crater (Oahu) only; however, similar specimens from Lanai have been seen. It is possible that this species is under-collected and/or misidentified as D. decipiens.