Bonaire lip fern

Acrostichum bonariense Willdenow, Sp. Pl. 5: 114. 1810; Notholaena aurea (Poiret) Desvaux

Stems short-creeping to compact, usually 4--8 mm diam.; scales bicolored, with broad, well-defined, dark, central stripe and narrow, light brown margins, narrowly lanceolate, slightly contorted, strongly appressed, persistent. Leaves clustered, 10--60 cm; vernation noncircinate. Petiole dark brown, rounded adaxially. Blade linear, pinnate-pinnatifid throughout, 1--4 cm wide; rachis rounded adaxially, lacking scales, with dense monomorphic pubescence. Pinnae articulate at swollen, hirsute nodes, basal pair slightly smaller than adjacent pair, ± equilateral, appearing hirsute adaxially. Costae absent. Ultimate segments elongate-deltate to ovate, not especially beadlike, the largest 1--7 mm, abaxially densely tomentose, adaxially hirsute. False indusia marginal, weakly differentiated, 0.05--0.25 mm wide. Sori ± continuous around segment margins. Sporangia containing 32 spores. n = 2 n = 90, apogamous.

Sporulating summer--fall. Rocky slopes and ledges; found on a variety of substrates though rarely observed on limestone; 1200--2400 m; Ariz., N.Mex., Tex.; Mexico; West Indies; Central America; South America.

Cheilanthes bonariensis has been assigned to Notholaena in past treatments. It is distantly related (at best) to the species here included in Notholaena , however, and we concur with R. M. Tryon and A. F. Tryon (1982) that it should be transferred to Cheilanthes . Chromosomal studies (G. J. Gastony and M. D. Windham 1989) suggest that C . bonariensis is an apogamous triploid that arose through autopolyploidy. Further investigation is necessary to determine whether 64-spored, sexually reproducing populations of C . bonariensis are still extant.