The Lycopodium obscurum Complex
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Section Obscura (Rothm.) Holub
Rhizome
subterranean, clothed with sparse, broad, rounded and scale-like microphylls;
aisodichotomously branched with one upright leafy aerial shoot and one
weak secondary rhizome produced each year, both positioned on the same
side of the rhizome, these alternating with those of the previous and
subsequent years; aerial shoots 8.0 - 19.0 (mean = 12.5) cm from soil
level to base of strobili, often producing secondary dormant meristems
at or near soil level; lateral branch systems 3 or 4, each branching dichotomously
to produce 8 - 16 lateral branchlets, annual constrictions evident; microphylls
spirally arranged but condensed into pseudowhorls of 3 or 4 per whorl,
oblanceolate, decurrent, those laterally positioned falcate to sub-falcate;
spores trilete, yellow, strongly reticulate on the distal hemisphere,
weakly so on the proximal hemisphere; gametophyte subterranean, holosaprophytic,
flattened, radially symmetrical, the upper margins frequently convoluted
and undulating, producing a ring meristem; n = 34, 2n = 68.
Growth of the aerial shoots is similar in all species. The shoots grow for 4 - 5 years and microphyll constrictions are evident along the length of the lateral branchlets. Section Obscura has a unique branching pattern to the rhizome that was well described by Primack (1973). The first year's growth typically results in an erect axis which remains below ground or is sub-emergent. After the production of this aerial shoot the rhizome elongates and produces a weak secondary rhizome on the same side as the aerial shoot. During the second year this pattern is repeated on the other side of the rhizome, and the previous aerial axis elongate and intitiates short lateral branches. Dichotomous branching of the lateral branch systems is concentrated in the third growing season, with occasional dichotomies occurring in the fourth season as well. Leaves of the lateral branchlets are 6- or 8-ranked and in 2 pseudo-whorls or 3 or 4 leaves apiece, producing phyllotactic fractions of 2/6 or 2/8. All leaves are strongly decurrent. Strobili, produced in the third and fourth growing season are sessile or sub-sessile, and terminal on either the main axis or on dominant branches of the upper lateral branch systems. Close examination of numbers of specimens show that it is not uncommon for the species to produce a short peduncular region subtending the strobili. One of the more common mutations in L. obscurum in eastern North America is the production of elongate axes in place of the strobili. These axes are initially indistinguishable from the elongate peduncles found in L. clavatum. These elongate axes may continue to grow for two or three seasons as indicated by the presence of annual constrictions, but in the latter periods of growth take on the normal phylotaxy of the lateral branchlets. These observations suggest that the absence of a peduncle in this group is a derived condition.
Based on the overall morphology of L. juniperoideum and a comparison of all members of the Section with the rest of Lycopodium, it seems apparent that L. juniperoideum is the basal member of the group. I would postulate that the synapomorphy for the other species is the phyllotactic reduction to 6 ranks from 8. Proximal branchlet regions in both L. obscurum, L. dendroideum and L. hickeyi pass through a 2/8 phyllotactic fraction identical to that of L. juniperoideum and occasionally the mature phyllotaxy is not realized. Such plants can show phyllotaxic fractions of 2/9, 2/8, 2/7 and 2/5. Lycopodium obscurum and L. hickeyi are monophyletic as evidenced by the appressed stem leaves (not found in the rest of Lycopodium s.s).
No confirmed hybrids have been identified in the group. There are, however, specimens which show morphologies intermediate between L. obscurum and L. hickeyi, between L. obscurum and L. dendroideum, and finally between L. hickeyi and L. dendroideum (Hickey, 1978). Flavonoid analyses (fusiak, 1982) failed to identify any differences among the North American members of the group. However, the distinctness of the North American taxa is supported by isozyme analyses, including the presence of a GPI gene duplication in L. obscurum (Terri Hildebrand, Dept. of Biology, Univ. of Kansas).
Key
to Species:
1. Leaves of the lateral branchlets predominantly eight ranked, in pseudo-whorls of four, narrow, 0.25 - 0.85 mm wide..................…......................................................................................................................L. juniperoideum
1. Leaves of the lateral branchlets predominantly six ranked, in pseudo-whorls of three, leaves broader 0.35 - 1.15 mm wide..................………… …….......................…..2
2.
Leaves of the lower portion of the main aerial axis diverging at angles
of 30 - 90°; leaves of the lateral branchlets arranged in 2 dorsal
and 2 lateral ranks, these with their adaxial surfaces facing down, and
2 ventral ranks, with their adaxial surfaces facing up……................................................……............................................................L.
dendroideum
2. Leaves of the lower portion of the main aerial axis appressed or diverging
at angles of less than 30°; leaves of the lateral branchlets arranged
in 1 dorsal and 2 upper lateral ranks with adaxial surfaces facing down,
and 1 ventral and 2 lower lateral ranks with adaxial surfaces facing up.........…….…................…..............................................................…3
3.
Leaves of all ranks linear-attenuate and essentially equal in size; all
leaves equally divergent from the branchlet axis and all lying in different
planes; leaf apex angle 21 - 36° (mean = 27°)..…….............................................L.
hickeyi
3. Leaves of the ventral rank linear-attenuate to long-triangular and
considerably smaller than those of the other ranks; leaves of the dorsal
and lateral ranks larger, linear-acuminate to linear-acute; dorsal and
ventral leaves commonly appressed to the branchlet axis, the lateral ranks
strongly divergent; leaves of the 4 lateral ranks generally lying in the
same plane, those of the dorsal and ventral ranks in a plane at right
angles to that of the laterals; leaf apex angle 27 - 59° (mean = 40°)…......................................................................................…........................L.
obscurum
Lycopodium
juniperoideum Sw.
vvvLycopodium
juniperoideum Sw., Syn Fil. 178, 401. 1806.
L. obscurum f. juniperoideum (Sw.) Takeda, Bot Mag. (Tokyo) 23:213.
1909. TYPE: "Habitat in Sibiria. Laxman", ex char.
vvvL.
dendroideum f. stricta Milde, fil. Europ. Atl., 254. 1867.
TYPE: "Sibiria orientalis versus mare Ochotense", Redowsk,. ex char.
vvvL.
japonicum, auct non Thunb., Maxim. In Mel. Biol. VII: 341. 1870.
Lower portion of the aerial shoot with leaves appressed to strongly divergent (0 - 900); leaves of the lateral branchlets in 8 ranks of 2 alternating pseudo-whorls, the first pseudo-whorl with dorsal, ventral and two lateral ranks, the next pseudo-whorl with 2 upper-lateral ranks and 2 lower-lateral ranks; the upper 5 ranks oriented such that the adaxial surfaces face down, the 3 lower ranks with their adaxial surfaces pointing up; free portions of the leaves linear-attenuate, 2.15 - 5.35 (mean = 3.85) mm long, 0.25 - 0.85 (mean = 0.60) mm wide, straight, not falcate, leaf apex angle of 14-350 (mean = 260); lateral branchlets essentially isophyllous; strobili 1 - 14 (mean = 2.8) per aerial shoot, 12.5 - 56.5 (mean = 30) mm long.
Distribution: Eastern Siberia, Japan, China, Taiwan, Korea, Bhutan, Philippines.
Notes: In Fl Pen. Kamtchatka 1:89. 1927, Komarov cites the combination "L. obscurum proles juniperoideum" and incorrectyl ascribes it to Takeda. In Hultén's Fl. Aleutian Is. 60. 1937, C. Christensen cites the combination "L. obscurum var. juniperoideum" and incorrectly ascribes it to Takeda. In Illus. Determing the Flora of Sibiria 51. 1909, Fedtshc. and Flerow cite the combination "L. obscurum var. strictum" and incorrectly ascribe it to Milde. Beginning with Maximowicz, numerous authors have used the name L. japonicum Thunb. for Asian members of the group. The only specimen in Thunberg's herbarium at Uppsala (IDC 1036: 1063 1.7) is obviously not L. juniperoideum or L. dendroideum but rather, appears to be a specimen within the L. clavatum group. In Index of the Lycopodiaceae, Øllgaard (1989) also lists L. juniperinum Sprengel as a homotypic synonym of L. juniperoideum.
Lycopodium
dendroideum Michx.
vvvLycopodium
dendroideum Michx., Fl. Bor. Amer. 2: 282.
1803. L. obscurum var. dendroideum (Michx.) Eaton, Gray's
Manual (ed. 6.) 696. 1890. L. obscurum f. dendroideum (Michx.)
Blomq. & Correll, J. Elisha Mitchell Soc. 56: 101. 1940. LECTOTYPE: Upper
left hand specimen of "in Carolina Septentrionalis", Michaux (P
- microfiche IDC 6211: 133 I.4), Hickey, Amer. Fern J 67: 47. 1977.
vvvL.
dendroideum f. flabellatum Midle, Fil. Europ. Atl. 254. 1867. L.
obscurum f. flabellatum (Milde) Takeda, Bot Mag. (Tokyo) 23: 212.
1867. TYPE: "Montes Da-chuang-Dingsa Manchuriae" Maack. Ex char.
vvvL.
obscurum var. hybridum Farwell, Rep. Mich Acad. Sci. 18: 91. 1916.
TYPE; Michigan, Keweenaw Peninsula, along the edge of woods and thickets,
Sept 1914, Farwell 3908 (holotype-BLH!).
vvvL.
obscurum var. dendroideum f. exsertum-furcatum Victorin, Contrib.
Lab. Bot. Univ. Montreal 3: 33. 1925. TYPE: Quebec, Kondiaronk, près de
la rivière Métabetthchouan, à 35 miles de son embouchure, 21 auôt 1922,
Victorin 15057 (holotype - MT, in part; isotype - GH!).
vvvL.
obscurum var. dendroideum f. exsertum
Victorin, Contrib. Lab. Bot. Univ. Montreal 3: 33. 1925. TYPE: Quebec,
Kondiaronk, près de la rivi è re Métabetthchouan, à 35 miles de son embouchure,
21 auôt 1922, Victorin 15057 (holotype - MT, in part; isotype -
GH!).
vvvL.
obscurum var. dendroideum f. monostachyon Victorin,
Contrib. Lab. Bot. Univ. Montreal 3: 33. 1925. TYPE: Quebec, lac à la
Barbotte, près de Saint Jérôme, comté de Terrebonne, 16 Septembre 1924,
Victorin 18012 (holotype - MT?), ex char.
vvvL.
obscurum subvar. parvispicatum Farwell, Amer. Fern J. 27: 19.
1937. L. obscurum f. parvispicatum (Farwell) Broun, Index
N. Amer. Ferns 110. 1938. TYPE: Michigan, Lake Linden, Oct 3, 1934, Farwell
10599 (holotype - BLH!).
Lower portion of the aerial shoot with leaves strongly divergent (30 - 90°); leaves of the lateral branchlets in 6 ranks of 2 alternating pseudo-whorls, each pseudo-whorl with 1 upper lateral, 1 lower lateral, and 1 lateral rank, but with opposite orientations; the upper 4 ranks oriented such that the adaxial surfaces face down, the 2 lower ranks with their adaxial surfaces pointing up; free portions of the leaves linear-attenuate, 2.35 - 5.45 (mean = 3.90) mm long, 0.45 - 1.15 (mean = 0.80) mm wide, falcate; leaf apex angle of 19-58° (mean = 37°); lateral branchlets basically isophyllous but with a slight tendency toward reduction in size of the lower ranks; strobili 1 - 14 (mean = 2.4) per aerial shoot, 12.5 - 56.5 (mean = 30) mm long.
Distribution: Labrador south to Pennsylvania, and in the Appalachians to North Carolina, west across northern United States and southern Canada to Alaska. In Asia from Kamtchatka south to Japan and Korea, west to eastern China.
Notes: Lectotypification of this species was first discussed by Morton (1967), but he did not clearly indicate any element of the collection as the lectotype. The lectotype was established by Hickey (1977).
Lycopodium
hickeyi. Wagner, Beitel & Moran
vvvLycopodium
hickeyi Wgner, Beitel & Moran, . L. obscurum
var. isophyllum Hickey, Amer. Fern J. 67: 47-48. 1977. TYPE: Pennsylvania,
Crawford Co., Woods and marsh nest to Powell Hollow, Rte 322, 2 miles
W of Cochranton, July 5, 1974, G. Williamson 91 (MU!).
vvvL.
obscurum var. dendroideum f. proliferum Vicotrin, Contrib.
Lab. Bot Univ. Montreal 3: 32. 1925. L. obscurum var. dendroideum subvar.
proliferum (Victorin) Farwell, Amer. Fern J. 27: 19. 1937. TYPE: Nova
Scotia, Yarmouth Co., Belleville, dry blueberry barren, Fernald & Long
23090 (holotype - GH!).
Lower portion of the aerial shoot with leaves appressed to slightly divergent (0 - 30°); leaves of the lateral branchlets in 6 ranks of 2 alternating pseudo-whorls, one pseudo-whorl with 1 upper and 2 lower lateral ranks, the other whorl with 2 upper lateral and 1 ventral rank; the upper 3 ranks oriented such that the adaxial surfaces face down, the 3 lower ranks with their adaxial surfaces pointing up; free portions of the leaves linear-attenuate, 2.50 - 5.00 (mean = 4.00) mm long, 0.35 - 0.95 (mean = 0.70) mm wide, strraight to slightly falcate; leaf apex angle of 21-36° (mean = 27°); lateral branchlets isophyllous with little or no tendency toward reduction in size of the lower ranks; strobili 1 - 10 (mean = 3.4) per aerial shoot, 15.5 - 61.5 (mean = 30.4) mm long.
Distribution: Newfoundland south through the Appalachians to Tennesse and west to Ohio,Michigan and Minnesota.
Notes: This species can tolerate drier regimes than either L. obscurum or L. dendroideum. It has a tendency to have a paler more yellow green coloration and a rounder branchlet cross-sectional shape.
Lycopodium
obscurum L.
vvvLycopodium obscurum
L., Sp Pl. 2: 1102. 1753. L. obscurum
var. genuinum Wherry, Guide to East. Ferns, 173. 1937. LECTOTYPE: plate
LXVII of Dillenius' " Historia Muscorum" as published in 1741,
Hickey, Amer. Fern J. 67: 48. 1977.
vvvL.
obscurum var. hybridum subvar. brevispicatum Farwell,
Amer. Fern J. 27: 19. 1937. L. obscurum var. hybridum f.
brevispicatum (Farwell) Broun, Index N. Amer. Ferns 111. 1938.
SYNTYPES: Michigan, Houghton Co., Lake Linden, Oct 3, 1934, Farwell 10603
(BLH!); "Bootjack, May 27, 1934, no. 9646" (Farwell?).
vvvL. obscurum var. obscurum
subvar. foliaceum Farwell, Amer. Fern J. 27: 19. 1937. L. obscurum
f. foliaceum (Farwell) Broun, Index N. Amer. Ferns 111. 1938. TYPE: Michigan,
Houghton Co., Lake Linden, Oct 14 1934, Farwell 10635 (holotype
- BLH!).
vvvL.
obscurum var. dendroideum subvar. breve Farwell, Amer. Fern
J. 27: 19. 1937. L. obscurum var. dendroideum f. breve (Farwell)
Broun, Index N. Amer. Ferns 110. 1938. TYPE: Michigan, Houghton Co., Lake
Linden, Oct 23, 1934, Farwell 10648a (holoype - BLH!).
Lower portion of the aerial shoot with leaves appressed to slightly divergent (0 - 30°); in 6 ranks of 2 alternating pseudo-whorls, one pseudo-whorl with 1 upper and 2 lower lateral ranks, the other whorl with 2 upper lateral and 1 ventral rank; the upper 3 ranks oriented such that the adaxial surfaces face down, the 3 lower ranks with their adaxial surfaces pointing up; free portions of the dorsal leaves linear-acuminate to linear-acute, appressed; leaves of the ventral rank much smaller than those of the other ranks and linear-attenuate to long triangular, appressed; lateral leaves twisted so as to lie parallel with those of the other ranks, divergent and often strongly falcate; 1.25 - 6.25 (mean = 3.60) mm long, 0.35 - 1.15 (mean = 0.80) mm wide, with a leaf apex angle of 27-59° (mean = 40°); lateral branchlets heterophyllous with estreme in size of the lower ranks; strobili 1 - 10[23] (mean = 2.9) per aerial shoot, 11.5 - 59.5 [78.5] (mean = 34) mm long.
Distribution: Southern Nova Scotia south in the Appalachians to northeastern Alabama and west to Wisconsin.
Notes: Dillenius' plate of L. obscurum was reengraved for post 1741 editions to depict a fertile specimen. The 1741 edition with the plate of a sterile specimen was designated the Lectotype by Hickey (1977). The specimen in the Linnaeun herbarium (LINN 1257.12) was rejected as the type because it is immature and cannot be identified to species. Wherry's L. obscurum var. genuinum is invalid.
The syntype, Farwell 10603 (BLH), for L. obscurum var. hybridum subvar. brevispicatum Farwell has Lectotype written on it, but to my knowledge this lectotypification has never been effectively published.
The type collection of L. obscurum var. dendroideum subvar. breve Farwell is mixed. It consists of a specimen on the left which is clearly L. obscurum and two other specimens which appear intermediate between L. obscurum and L. dendroideum. Since the left hand specimen is the only element that can be clearly identified to taxon, it probably should ultimately be identified as the lectotype.
References:
Fuskiak, F.
1982. Flavonoid chemistry of the North American Lycopodium obscurum
complex. Amer. Fern J. 96.
Hickey, R. J. 1977. The Lycopodium obscurum complex in North America. Amer. Fern J. 67: 45-48.
Hickey, R. J. 1978. Variability in the Lycopodium obscurum complex of North America and Eastern Asia. MS thesis, vvvMiami University, Oxford, Ohio.
Morton, C. V. 1967. The fern herbaria of André Michaux. Amer. Fern J. 57: 166-182.
Øllgaard,
B. 1989. Index of the Lycopodiaceae. Biolog. Skr. 34, Kongel. Danske Vidensk.
Selsk., Copenhagen:
vvv 1-135.
Primack, R. 1973. Growth patterns of five species of Lycopodium. Amer. Fern J. 63: 3-7.
Wilce, J. 1972. Lycopod spores, I. General spore patterns and the generic segregates of Lycopodium. Amer. Fern vvvJ. 62: 65-79.