Asplenium, L.

1. Asplénium L. View in CoL 3

Rhizomes short, erect or occasionally creeping, with dark, lineartriangular to linear-lanceolate, sometimes filiform scales. Leaves in apical tufts; petiole dark, at least at the base, often glabrous; lamina entire or variously dissected; veins free. Sori elliptical to linear; indusium resembling the sorus in shape and size, usually opening towards the vein.

Many interspecific hybrids have been recorded but, with one exception (16x 5), are not frequent enough to be mentioned individually. (For list of hybrids see A. H. G. Alston, Proc. Linn. Soc. London 152 (2): 132-44 (1940) and D. E. Meyer, Amer. Fern Jour. 50: 138-45 (I 960).)

1 Leaves simple, cordate to palmately lobed 1. hemionitis 1 Leaves compound, not cordate or palmately lobed

Leavesdichotomously forked or 3- partite

5 Leavesusually 2-or4-partite, leaf-segments ± linear

16. septentrionale ! Leavesusually3 -partite, leaf-segments narrowly rhombic

17. seelosii Leavesneitherdichotomously forked nor 3-partite

1 Leavesi-pinnate

5 Atleastsomescaleswithdarkopaquecells; rhachis brown orblack,brittle

6 Petiolewithdenseglandularhairs 3. petrarchae 6 Petiole± glabrous

7 Pinnaemorethan twice aslong as wide, usually with only onelongsorus 4. monanthes 7 Pinnae less than twice as long as wide, usually with several small sori (often appearing confluent at maturity)

8 Rhachisgreen atapex; lamina thin, light green

6. adulterinum 8 Rhachisreddish-black throughout; lamina thick, dark green 5. trichomancs 5 Scales composedofhyalinecells; rhachisgreen (orifblack, thenstoutand not brittle)

9 Lamina2- 4cmwide,coriaceous 2. marinum 9 Lamina1- 2cmwide,notcoriaceous

10 Pinnaesuborbicular, shortly stalked 7. viride 10 Pinnaeoblong, adnate to rhachis 8. jahandiezii 4 Leaves2-or3-pinnate

11 Leaves2-pinnate

12 Leavesdeflate; base of petiole swollen; sori lying next to midrib (13-15). adiantum-nigrum group 12 Leavesellipticto ovate (ifalmost deflate, then sori nearer tomargin than to midrib); base of petiole not swollen

13 Rhizomemuch-branched, densely caespitose; ultimate leaf-segments ± rhombic, distant

14 Laminaglandular; ultimate segments crenately lobed

19. lepidum 14 Laminaeglandular; ultimate segments finely toothed

18. ruta-muraria

13 Rhizome rarely branched, not densely caespitose; ultimate leaf-segments ± ovate, not distant 15 Lamina narrowly elliptical; lowermost pinnae distinctly shorter than the rest 9. fontanum 15 Lamina ovate to lanceolate; lowermost pinnae not distinctly shorter than the rest 16 Lamina lanceolate; sori near midrib 10. forisiense 16 Lamina ovate-lanceolate; sori near margin (11-12). obovatum group

11 Leaves 3-pinnate

17 Lamina lanceolate; pinnules palmately dissected 20. fìssum

17 Lamina deltate; pinnules pinnately dissected (13-15). adiantum-nigrum group