Diphasiastrum xverecundum (Lycopodiaceae), nothosp nov

7 Pages·2003·2.8 MB·Latin

by  A V Gilman

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.