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RHODORA, Vol. 105, No. 922, pp. 136-142, 2003 XVERECUNDUM DIPHASIASTRUM (LYCOPODIACEAE), NOTHOSP. NOV. Arthur Oilman V, & William D. Countryman Environmental Assessment Planning, VT Winch 868 Road, 05658 Hill Northfield, [email protected] e-mail: ABSTRACT. Fouf live clones of the rare hybrid lycopod, Diphasiastrum X complanatum digitatum, have been located and studied northern New England. in This plant described and a binomial provided. is Key Words: Lycopodiaceae, Diphasiastrum, hybrid Four orthospecies and up to six hybrids of Diphasiastrum Holub, the flat-branched lycopods, occur in the hilly to mountainous highlands of New Vermont, Hampshire, and Maine. not unusual It is to find several species and growmg hybrids (< together within small ha) habitat 1 Wagner Wagner and land present an study hybridism in the genus. and chyiim (Pursh) Holub most commonly are the encountered species in land The fourth local orthospecies, D. sitchense (Rupr.) Holub, primarily alpine is New England in and consequently seldom occurs mixed genus com- in munities. Three hybrids are occasionally encountered communi- such in D. ties: Xsabinifoliiim (Willd.) Holub (= D. X sitchense tristachyiim\ D. Xhabereri (House) Holub X (= D. digitatiim tristachyum\ and Z). Xzeilleri (Rouy) Holub (= D, complanatum X Two tristachyum). known {^o\xy)\{o\\xb[=D. X alpiniim{L.)Y{o\uh complanatum; Wilce and D. digitatum Xsahinifolium (Gilman 1994). The known sixth hybrid from the region Diphasiastrum is X complanatum digitatum. According Wilce to (1965, p. 160), is it the "rarest of the group of hybrids involving [D. complanatum, D. digitatum, and D. tristachyum]." In a thorough study of herbarium specimens from Quebec, Wilce (1965) scored 95 specimens of the putative parents for morphological characters and found only three fully 136 — Oilman 2003] Diphasiastrwn Xyereciindwn 37 1 intermediate hybrids, although others shared some characteristics of 1 1 both parents. Altogether, she was able to cite only 19 specimens of this hybrid, ranging from Quebec and Maine to Ontario, Wisconsin, and New Minnesota, south to Hampshire, Vermont, and Connecticut. How- no Wagner ever, she observed living populations, and Beitel (1993) uncommon" stated that the hybrid ''seemingly but "probably far more is common My than collections indicate." observations indicate that in New northern England, rare but not significantly more so than it is D, Xhabereri or D. XzeillerL I have located and studied four extant may populations, each of which consist of a single clone. Although Wilce (1965) reported partial spore abortion in several Diphasiastrum hybrids, mostly well-formed, presumably viable spores X were observed in the D. compJanatum digitatum hybrids reported here. Spore viability and the nearly identical morphologies of the four clones studied both suggest not just isolated individuals, but a real group of lineages able to persist over time. Therefore, recognition of the taxon as a nothospecies reproductively competent species of hybrid origin) (a merited. Both D. digitatum var. amhiguiim Vict. (Victorin 1925) and is D. complanatum gartonis B. Boivin (Boivin 1960) were suggested var. by their authors to apply to plants of this hybrid origin, but have been referred D. Xhabereri and D. Xzeilleri, respectively (Wilce 1965). to Oilman Macwahoc W of U.S. Rt. 2A, near N. Yarmouth Academv Grant MAINE complanatum Diphasiastrum hybrida Planta clavigerens, inter et D. digitatum multum utrumque similata, sed pedunculo longiore, orta; non saepius quattuor a primo, ab altero robustiore, strobilis flexile, ramibus flabelliforme differt. > m, branching and Rhizome indeteminate, long-creeping to freely 1 1.5- forming large clonal patches, superficial to slightly buried, terete, mm 2.3 diameter, loosely invested with widely spaced, short, narrow in mm mm "leaves"), these 1.8-3.0 long, 0.5-1.0 microphylls (hereafter cm 10-16 wide base. Upright branch systems determinate, tall (or at mm 15-25 cm); axes 1.5-2 with peduncles and strobili to terete. in mm diameter, with widely spaced, short, narrow leaves, these 1.0-2.0 Rhodora 138 105 [Vol. Mi ^+ E mm 1 » ^ F i ^' d 'y 1 '^' ft* * ' mm 1 cm 10 Figure Diphasiastrum Xverecundum. 1. A. Habit of one upright branch system. B. branchlet tip, dorsal view. C. Branchlet with annual constriction, ventral view showing stomata (schematic). D. Sporophyll, abaxial. E. Sporophyll, adaxial, with sporangium dehiscence. at F. Peduncle, G pedicels, and base of Habit of strobili. A-F entire plant. drawn from Gilman 94349 G (nebc); drawn from Gilman 97395 (nebc). — Gilman 2003] Diphasiastrum Xverecundum 39 1 mm long, 0.5-1.0 wide at base. Lateral branches spreading, dorsiventral, mm complanate, 1-2 wide, 4-7 cm (3-) (-8) long, (1-) 2 (-3) dichotomized, with 2/2 phyllotaxy; annual growth constrictions evident. Dorsal and lateral leaves prominent, each width of branch, 2.5-3 ca. 1/3 mm (4) long. Lateral leaves adnate for 0.8 their length, leaf tips hyahne, cuspidate, normally branch porrect, parallel to orientation, appressed or < mm (in shade forms) spreading. Ventral leaves appressed, minute, 1.0 < mm wide at base, 2.0 long, narrowly triangular with hyahne tip. Stomata abundant on branch on ventral surface, lacking dorsal surface. Fertile branches similar to main axis of upright branch systems, erect, mm terete or (if reclining) slighdy complanate, 1.5-3 in diameter, (5-) mm 10-20 (-30) long, closely invested with numerous short, broad leaves imbricate in apparent 1/7 or 1/8 phyllotaxy; stomata abundant on abaxial leaf surfaces. Peduncles erect, slender but not flexuous, 0.8-1.2 mm cm 3-6 in diameter, (2-) (-7) long, often twice dichotomized to form 4 pedicels, angle of dichotomy narrow, 35''-40'^. Peduncle leaves somewhat scattered, narrow, hyaline, usually spreading. Pedicels often mm four, with scattered spreading narrow leaves, slender, 0.5-0.9 in mm 5-15 diameter, altogether (from base of dichotomy) long, first mm individually (from base of second dichotomy) 2-11 long, Strobili mm l-A with well-defined bases, 3 in diameter, (1.6-) 2.0-2.5 (-5), cm (-3.0) long. Sporophylls subpeltate, spade-shaped, tips cuspidate, margins spreading maturity, central portion green, hyaline, erose. at many hundred each sporangium, Sporangia reniform. Spores in well- 35^0 prominently formed, yellow, surfaces reticulate, |im. trilete, unknown Gametophyte parents top- or carrot-shaped, subterranean, (in Chromosome number undetermined achlorophyllous, mycotrophic). — 23 (n in parents). ETYMOLOGY. The spccific epithet refers to the bashful nature of this which shows no outstanding features, and consequently taxon, is rare, is know organic HABITAT andy observed were growing mixed-genus Three of the four clones in Diphasiastrum communities with four other taxa, including the least at population was associated only with D. putative parents; the fourth mowed The an old havfield, annually. transmission lands and Rhodora 140 105 [Vol. Associated plant species, in addition to other Diphasiastnim taxa, members included of the regional upland flora typical of infertile soils, such mosses Polytrichum juniperinum Hedw., Hedw., as the P. piliferum and Thiiidium delicatulum (Hedw.) BSG; clubmosses Lycopodium & W, clavatum H. Wagner, Moran, and lagopus L., L. hickeyi Beitel L. Kuhn Zinserl. ex Kuzen; fems Pteridium aquiUnum (L.) var. latiusculum Underw. (Desv.) ex Heller, Dennstaedtia punctilobula (Michx.) T. Moore, and Thelypteris noveboracensis Nieuwl.; grasses Agrostis (L.) perennans capillahs L., A. (Walter) Tuck., Brachyelytrum erectum & Koyama (Schreb. ex Spreng.) P. Beauv. var. glahratum (Vasey) Kawano, Bromiis Danthonia and ciliatus L., spicata (L.) F. Beauv., Dichanthelium boreale (Nash) Freckmann; forbs Anaphalis margarita- & cea (L.) Benth. Hook., Antennaria neglecta Greene canadensis var. (Greene) Cronquist, Cornus canadensis Euthamia L., graminifolia (L.) Hieracium Nutt., pilosella L., Lysimachia quadrifolia L,, Solidago nemoralis Alton; and low shrubs Rubus hispidus Gaidtheria L., procumbens Vaccinium L., angustifoliiim Alton, and Spiraea alba Duroi var. (Alton) Dippel. latifolia Diphasiastrum Xverecundum much D. complanatum and D. is like digitatum, but from more it differs the first in a longer, less flexuous, and and branches lateral The than due difficult to assess to variation. also has somewhat the straggling It or discomposed habit of D. complanatum and lacks the regular, fanlike branching habit normally that strongly characterizes D. digitatum. Wilce intermediacy intemi ance. There are no unique, idiosyncratic, or transgressive characters that allow immediate recognition. Field mixed identification aided is in communities by comparison with living material of the other taxa, es- pecially if one is familiar with progenitors its as well as with Dipha- siastrum tristachyum and hybrid progeny. Of some its aid in recognition are the small size and narrow shape of the ventral leaves (Figure IC), by features shared its progenitors but different from the typically longer and wider ventral leaves of D. tristachyum. In D. Xverecundum has life, a bright, emerald green color, quite dissimilar from the yellow-green — Gilman Diphasiastrum Xverecundum 2003] 141 color of D. from typical digitatum, the dull, darkish-green to yellow- green color of D. complanatum, and from the glaucous blue-green color of D. thstachyum and hybrids. Plants from shaded its habitats are particularly difficult to assess, as are dried and pressed specimens. Therefore, the above description is based on plants from the four living populations observed, occurring open, sunny all in habitats. Relationships Diphasiastrum are unresolved and presumed in the hybrid origin of taxa of intermediate morphology has not been fully = demonstrated. At least some hybrids are homoploids with diploid {2n 46) chromosome numbers (Hersey and Britton 1981; Wagner 1980, 1992). Although Whittier and Britton (1995) succeeded in culturing gametophytes from spores of Xhabereri, Diphasiastrum Z). is difficult to cultivate and no hybrid has been produced in culture. Stoor et al. (1996) concluded isozyme banding pattems (phosphoglucoisomerase additive X and esterase) supported a hybrid origin {D. alpinum tristachyum) for named the European plant they D. oeUgaardii, but such pattems are not Rumsey logically unequivocal for homoploid taxa (Vogel and 1999). which chromosome Unlike taxa of allopolyploid origin, in a multiplied complement convincingly argues progenitors must have preceded that banding pattems homoploids might derivatives, so-called "additive" in Indeed, Vogei and indicate segregating, not hybridizing, lineages. Rumsey (1999) questioned the validity of the hybrid hypothesis for this would have However, improbable divergent speciation reason. that it is many morphological resulted in taxa intermediate in so characters as those observed. The group indeed presents a difficult puzzle that invites by imaginative means. further investigation ADDmoNAL Maine: Aroostook Co., Haynesville, large clone specimens: at U.S.A. W S edge of powerline corridor, just of the village of Haynesville and just upslope of U.S.^Rt. 2A, 24 Aug 2000, Gilman 2K186 (maine, nebc). Vermont: Essex Co., grown Concord, on old pasture land under powerlines (the adjacent areas having up Gilman 99220 to boreal forest), near Joslin Turn, 19 Sep 1999 et seqq. (vr, nebc); Lamoille Co., Wolcott, one large clone, old pasture, north of Eastman Cross Road, 19 Nov 1994 Gilman 94349 (vr, nebc). et seqq., me accompanying acknowledgments. thank the following for in I and Johannes Voeel, Terri Hildebrand Wagner Wagner, Warren ''Herb" Florence Horn, Wilfried Bennert, Jr.f, David and David Conant; also Robert Preston for Harrington, two thank reviewers and review of specimens. I also for discussions my improved understanding of the genus eomments significantly that improved paper and and have, hope, this as well. difficulties that I its 142 Rhodora 105 [Vol. LITERATURE CITED BoiviN, B. 1960. Centurie des plantes Canadiennes Contrib. No. de III. 32, Inst, Recherche sur les Vegetaux, Ministere de T Agriculture, Ottawa, Canada. Extrait du Naturaliste Canad. 25-29. 87: A GiLMAN, A. V. 1994. new X tri-hybrid lycopod, Diphasiastrum digitatum Rhodora sabinifolium, 96: 287-29:^. AND a hybrid taxon of Lycopodium (section Complanata) in Ontario. Canad. J. Genet. 497-504. Cytol. 23: Stoor, a. M., M. Boudrie, C. Jerome, K. Horn, and W. Bennert. Dipha- 1996. siastrum oellgaardii (Lycopodiaceae, new Pteridophyta), a lycopod species from central Europe and France. Feddes Repert. 107: 149-157. Victorin, Fr. Marie-. 1925. Les lycopodinees et leurs formes mineures. Contr. Lab. Bot. Univ. Montreal Montreal, Canada. 3, VoGEL, C. AND RuMSEY. On J. F. 1999. J. the status of Diphasiastrum oellgaardii (Lycopodiaceae, Pteridophyta). Feddes Repert. 110: 439-445. Wagner, Chromosome F. S. 1980. behavior in three interspecific hybrids of Diphasiastrum (Lycopodiaceae). Misc. Publ. Bot. Soc. Amer. 121-122. 158: 1992. Cytological problems Lycopodium in Ann. . sens. Missouri Bot lat. Card. 718-729. 79: Wagner, W. and M. H., Jr. J. Beitel. 1993. Lycopodiaceae, pp. 18-37. In: Flora of North America Editorial Committee FInm ^f Wr^rtk a^^^,>.. ki^^u eH<5 „j? mnosperms New and York. AND Wagner. F. S. 1983. Genus communities New study of World Botrychium (Ophioglossaceae). Taxon 32- 51-63 WHrrriER, D. and M. P. D. Britton. 1995. Gametophytes of Diphasiastrum Xhabereri. Amer. Fern 85: 89-94. J. Wilce, H, J. 1965. Section Complanata of the genus Lycopodium. Nova Beih. Hedwigia 19: 1-233.