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BFNA Title: Scorpidium |
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Calliergonaceae - Scorpidium XX. SCORPIDIUM (Schimper) Limpricht, Laubm. Deutschl. 3: 570. 1899 *
[Latin scorpio, alluding to shoot apex like a scorpion tail] Hypnum
subg. Scorpidium Schimper,
Syn. 650. 1860; Limprichtia Loeske. Plants medium-sized to very robust, sometimes
turgid, green, brownish yellow, brownish to blackish red or red. Stem irregularly to pinnately
branched ± in one plane, with weak central strand (rarely lacking) and at
least a partial outer hyalodermis, cells inside cortex thin-walled;
pseudoparaphyllia broad; rhizoids or rhizoid initials on stem at or just
before leaf insertions; axillary hairs with 2--9(--11) distal hyaline cells. Stem leaves from erecto-patent base
suddenly curved in distal portion, sometimes indistinctly so or ± straight,
ovate-lanceolate to broadly ovate (sometimes almost orbicular), with obtuse,
apiculate, acute or acuminate apex, not or hardly plicate, concave or
strongly concave; margin finely denticulate or ± entire near leaf apex,
entire proximally; costa either long and single, ending in distal half of
leaf, or short and single or double (rarely absent); median lamina cells
thin-walled to strongly incrassate, eporose to porose; differentiated alar
cells 2--20, shortly to longly rectangular, thin-walled and hyaline, strongly
inflated, in small transversely triangular group, not or hardly decurrent. Sexual condition dioicous or autoicous; inner perichaetial
leaves plicate; vaginula with paraphyses. Capsule curved and ± horizontal; annulus separating; exostome
reticulate or partly (rarely entirely) basally cross-striolate externally,
margin slightly dentate distally. Spores
12--21 \um. Scorpidium
species are
characterized by a hyalodermis of inflated, thin-walled epidermis cells,
which is present in at least part of the stem circumference. Unlike Hamatocaulis
species, they have at least a weak central strand in the stem, except in
very weak plants. They have small alar groups consisting of a few (2--20)
inflated and thin-walled cells that are sharply delimited from the
surrounding cells. Their stem leaves are normally smooth and, like those of Hamatocaulis,
from an erect base suddenly curved above, except in most expressions of S.
scorpioides. Although S. scorpioides superficially looks very
different from the other two members of the genus, these differences are
mainly found in characters, such as size and leaf shape, that affect the
appearance of the plant to the naked eye. On the other hand, molecular
evidence and critical microscopic features of, e.g., stems, alar cells, and
exostomes relate this species to S. cossonii and S. revolvens.
Based on molecular evidence, Scorpidium scorpioides is an ingroup
within S. cossonii, and is thus an
example of a species with a number of autapomorphies that are easily visible
to the naked eye, in a genus where the two other members have a more
generalized appearance. Scorpidium species are found in mineral-rich
to intermediately mineral-rich and normally nutrient-poor habitats. When
mineral-rich these habitats are mostly rich in calcium. Species
3 (3 in the flora): widely distributed in the Holarctic region, with
scattered occurrences in more southern areas (also in the southern
hemisphere). SELECTED
REFERENCES Hedenäs, L. 1989. The genera Scorpidium
and Hamatocaulis, gen. nov., in 1.
Stem leaves strongly concave, almost orbicular and obtuse to apiculate, or
from broadly ovate to broadly ovate-lanceolate base narrowed to apiculate,
acute or acuminate point, falcate or (rarely) straight; costa usually double,
more rarely single or lacking, rarely reaching above mid-leaf; hyalodermis of
stem often incomplete; stem leaves ca. (0.7--)1--2.4 mm wide . . . 3. Scorpidium
scorpioides 1.
Stem leaves concave, from ovate to ovate-lanceolate base narrowed to shortly
to longly acuminate apex, falcate; costa single, ending in upper half of
leaf; hyalodermis of stem complete; stem leaves ca. 0.5--1.1 mm wide. 2.
Autoicous; mid-leaf cells 61--140(--179) \um, with shortly to longly
fusiform-narrowed cell ends; outer peristomial layer usually predominantly
(more than 40--50%) cross-striolate basally . . . 1. Scorpidium
revolvens 2.
Dioicous; mid-leaf cells of stem leaves 14--95(--120) \um, with square to
shortly fusiform-narrowed cell ends; outer peristomial layer of exostome
predominantly (more than 70%) dotted basally. . . . 2. Scorpidium cossonii 1. Scorpidium revolvens (Swartz ex Anonymo) Rubers in A. Touw & W. V. Rubers,
De Nederlandse Bladmossen 380. 1989 Hypnum
revolvens Swartz ex
Anonymo, Monthl. Rev. 34: 538. 1801; Drepanocladus revolvens (Swartz
ex Anonymo) Warnstorf; D. revolvens var. miquelonensis (Renauld
& Cardot) Grout; Limprichtia revolvens (Swartz ex Anonymo) Loeske Plants medium-sized to robust (sometimes when
submerged), not turgid, shoot apex not hooked, green, red, purplish red, dark
brownish red or blackish red. Stems sparsely
and irregularly or more rarely ± pinnately branched, with well-developed,
complete hyalodermis. Stem leaves from
erecto-patent or patent base ± suddenly curved distally, ovate or
ovate-lanceolate, gradually narrowed to acuminate or longly acuminate apex,
sometimes near apex suddenly narrowed to apiculus, ca. 0.5--1 mm wide,
concave; costa single, ending in distal half of leaf; median lamina cells
(shorter half of leaf) 61--140(--179) \um, cell ends shortly or longly
fusiform-narrowed (rarely rounded to almost square), differentiated alar
cells 2--10. Sexual condition autoicous.
Peristome: proximal outside of
exostome predominantly (more than 40--50%) cross-striolate basally. More
or less common except in regions with strongly calcium-rich soils or bedrock
in the boreal and Arctic zones, farther south mainly in mountainous areas,
intermediately mineral-rich and often spring-influenced fens, small
periodically water-filled depressions, shores or, more rarely, submerged;
0-3020 m; Greenland; St. Pierre and Miquelon (Miquelon); Alta., B.C., Nfld.,
Man., N.W.T., Nunavut, Ont., Que., Sask., Yukon, Alaska, Colo., Idaho, Mich.,
Minn., Mont., Ohio, Vt., Wis., Wyo.; South America; Eurasia (including Papua
New Guinea); s Africa, Pacific Islands (New Zealand); Antarctic. This
species has often been confused with S. cossonii, and the differences
between these species are discussed under the latter. 2. Scorpidium
cossonii (Schimper) Hedenäs, Lindbergia 15: 18. 1989 Hypnum cossonii Schimper,
Musci Eur. Nov. Bryol.
Eur. Suppl. fasc. 3--4 (Mon.): 5, 5. 1866; Limprichtia cossonii (Schimper)
L. E. Anderson, H. A. Crum & W. R. Buck; Drepanocladus intermedius (Lindberg)
Warnstorf; D. revolvens subsp. intermedius (Lindberg) Grout; D.
revolvens var. intermedius (Lindberg) L. R. Wilson Plants medium-sized to robust (sometimes when
submerged), rarely slender, not turgid, shoot apex sometimes slightly hooked,
green, yellow-green, brown or brown-red. Stems
pinnately or sometimes irregularly branched, with well-developed,
complete hyalodermis. Stem leaves from
erecto-patent or patent base ± suddenly curved distally, ovate or rather
broadly ovate, gradually narrowed to shortly or longly acuminate apex, near
apex often suddenly narrowed to apiculus, ca. 0.5--1.1 mm wide, concave;
costa single, ending in upper half of leaf; median lamina cells (shorter half
of leaf) 14--95(--120) \um long, cell ends square, rounded or shortly
fusiformly narrowed, differentiated alar cells 2--10(--15). Sexual condition dioicous. Peristome: lower exostome outside
predominantly (more than 70%) dotted basally. Common
in regions with calcium-rich soils or bedrock in the boreal and Arctic zones,
farther south mainly in mountainous areas, ± calcium-rich habitats in fens,
springs, periodically water-filled depressions, shores or, more rarely,
submerged; 0-3650 m; Greenland; Alta., B.C., Man., Nfld., N.W.T., Nunavut,
N.S., Ont., Que., Sask., Yukon; Alaska, Colo., Conn., Ill., Iowa, Maine,
Mich., Minn., Mont., N.J., N.Y., Ohio, Vt., Wis.; South America, Eurasia,
Pacific Islands (New Zealand). Scorpidium
cossonii is often
confused with S. revolvens or Hamatocaulis vernicosus. From the
latter it is easily separated by its hyalodermis and the usually present
central strand of the stem, and by its differentiated hyaline and inflated
alar cells of the stem leaves. Hamatocaulis vernicosus, which
lacks all these features, usually has distinctly plicate stem leaves, whereas
these are smooth in S. cossonii. Scorpidium cossonii differs
from S. revolvens in being dioicous (the latter is autoicous) and in
having shorter mid-leaf cells in the stem leaves. The ends of these cells are
square to shortly fusiform-narrowed in the first species whereas they are
shortly to longly fusiform-narrowed in the latter. Both species may have red
or strongly red colors, and in such cases S. cossonii is usually
brownish red while S. revolvens is mostly blackish or purplish red.
Due to a large variation in both species, especially when herbarium material
is also considered, color should, however, be used with care in identifying
specimens. Dark purplish plants usually belong to S. revolvens and
predominantly green or yellow-green plants with a brown-red costa or costa
and leaf base belong to S. cossonii. The differences in leaf
areolation between the two species make S. cossonii less glossy than S.
revolvens, but this character, like the difference in size and branching
pattern (S. cossonii is slightly smaller and more richly and regularly
branched than S. revolvens), which is obvious in mixed collections, is
often difficult to use in identification without much experience. In mixed
collections S. cossonii has more shortly acuminate stem leaves than S.
revolvens, but both species are variable in this character and the
overlap between them is great. 3. Scorpidium
scorpioides
(Hedwig) Limpricht,
Laubm. Deutschl. 3: 571. 1899 Hypnum
scorpioides Hedwig,
Sp. Musc., 295. 1801 Plants robust or very robust, occasionally
medium-sized, turgid plants, often with a characteristic claw-like shoot
apex, green, brown or often red to blackish red. Stems mostly sparsely or irregularly pinnately branched, with
partial or complete hyalodermis (more than 25% of stem circumference). Stem leaves from erecto-patent to
patent base usually rather suddenly curved distally, rarely straight or
almost so, varying in shape from almost orbicular to broadly
ovate-lanceolate, suddenly narrowed to obtuse and mostly apiculate point or
more gradually narrowed to acute or acuminate point, ca. (0.7--)1--2.4 mm
wide, strongly concave; costa double or occasionally single (rarely absent),
reaching somewhere below to very rarely slightly beyond middle of leaf, when
single often branched; median lamina cells (shorter half of leaf)
32--200(--210) \um, cell ends square, rounded or shortly fusiformly narrowed,
differentiated alar cells 5--20. Sexual
condition dioicous. Peristome: proximal
outside of exostome varying from almost entirely cross-striolate to almost
entirely dotted. Common
in many areas in the north, and in the Arctic, rich or intermediate habitats
in fens, pools, lake shores or submerged in lakes; 0--3550 m; Greenland;
Alta., B.C., Nfld., Man., N.B., Nfld., N.W.T., Nunavut, N.S., Ont., Que.,
Yukon; Alaska, Colo., Conn., Ind., Maine, Mich., Minn., Mont., Utah, Vt.,
Wis., Wyo.; South America; Eurasia; Australia. Scorpidium
scorpioides is usually
easily known by its large size and strongly concave, broad and usually
shortly pointed leaves with a short single or double costa. Straight-leaved
phenotypes, which are rare, look very different from the falcate-leaved ones,
but, except for the leaf curvature, there does not seem to be any difference
between these phenotypes. Specimens with straight leaves could be confused
with Pseudocalliergon turgescens and the differences between the two
are given under the latter. |
