Campyloneurum angustifolium (Sw.) Fée
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Authority
Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.
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Family
Polypodiaceae
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Scientific Name
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Description
Species Description - Rhizomes short-creeping, pruinose, 3–5 mm diam.; rhizome scales dense at the rhizome apices, dark brown, lanceolate, 3–6 x 0.7–1(–1.5) mm, clathrate, the cells elongate, at least twice as long as wide; fronds 15–70 cm long, clumped; stipes absent or extremely short, 2 cm long, usually not clearly demarcated; blades subcoriaceous, linear, 0.5–1.2(–1.6) cm wide, bases gradually tapering, apices long-acuminate; lime dots absent adaxially; areoles 1 or 2(–3) rows between midribs and margins, excurrent veinlet 1 per areole; main lateral veins immersed and not discernible, secondary veins irregularly anastomosing; sori mostly in single or irregular double rows running the length of the blades, one ± regular or two irregular rows on each side of the midrib; 2n=74 (Peru), 148 (Jam, CR).
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Discussion
Polypodium angustifolium Sw., Prodr. 130. 1788. Type. Jamaica. Swartz s.n. (S, not found; isotypes BM, LD, S).
Unverified, Doubtful, or Mistaken Reports. DF (reported by Mickel & Beitel, 1988, and Mickel, 1992, but not verified). Me´x (reported by Mickel & Beitel, 1988, and Mickel, 1992, but not verified; also reported by Tejero-Di´ez & Arregui´n-Sanchez, 2004, but specimens are C. amphostenon). Son (Van Devender 95-902, ARIZ, MO, UCR, USON, reported by Reina Guerrero in Madron˜o 44:209. 1997, but not verified; specimens could be C. ensifolium).
Smith (1981), Stolze (1981), Mickel and Beitel (1988), Leo´n (in Tryon & Stolze, 1993; in Davidse et al., 1995), and many others, in floristic accounts, have chosen to synonymize C. ensifolium under C. angustifolium, or have ignored it altogether. We now believe that it is subtly distinguishable, and occupies a more-or-less discrete range. However, further study, especially cytological and isozymic, is needed. The marked variation in cell size and shape of rhizome scales of C. angustifolium s.l. suggests to us that hybridization and polyploidy may be responsible for some of the differences seen. Even with the removal of C. ensifolium, there is an element within the C. angustifolium complex in Mexico that appears to be substantively different. This entity, confined to southern Mexico and probably northern Central America, has the rhizome scales darker brown, narrower (1 mm wide), with the cell lumina very narrow (lateral walls wider than the lumina). This variant almost always occurs at lower elevations than C. angustifolium, usually below 1000 m (vs. above 1000 m for C. angustifolium s.str.; it is also much less common in Mexico than is C. angustifolium. We regard it as probably distinct specifically, but are unable to find an existing name for it; pending further study, we include it in a broad concept of C. angustifolium. Because of the narrow rhizome scales with small cell lumina, the species approaches what has been called C. angus tipaleatum (Alston) Lellinger, known from Colombia to Bolivia. Specimens of this narrow-scaled form include the following, three of which were cited as C. angustifolium by Leo´n (marked by an asterisk*): Chis (*Palacios-Rios 2884, UC). Oax (Mickel 5792, UC; *Nee 32158, UC; Wendt et al. 4007, UC). Tab (Cowan 3423, UC). Ver (Calzada 10263, UC; Copeland herb. 154, MEXU, UC; *Paxson et al. 17M680, UC). Judging by the scales, C. angustifolium is probably more closely related to C. amphostenon, which has similar rhizome scales, than it is to the narrow-scaled variant with very narrow cell lumina mentioned above. A few specimens seem somewhat intermediate and difficult to place in one species or the other, e.g., Camp 2740 (UC), from Oaxaca. One collection listed above, from San Luis Potosi´, was cited under C. densifolium by Leo´n (1992); we discuss C. densifolium under C. amphostenon.