Ditrichum pusillum

(Hedwig) Hampe

Flora 50: 182. 1867,.

Basionym: Didymodon pusillum Hedwig Sp. Musc. Frond., 104. 1801
Synonyms: Ditrichum tortile (Schrader) Brockmuller Trichostomum tortile Schrader Trichostomum tenue Hedwig Weissia capillacea Bridel
Treatment appears in FNA Volume 27. Treatment on page 455. Mentioned on page 450, 454, 456.

Plants small, to ca. 1 cm, forming dull green tufts. Stems 0.4–1.2 cm, simple. Leaves to ca. 3.5 mm, erect-patent, weakly secund, lanceolate to linear-lanceolate, gradually acuminate to a channelled subula, acute, lamina 1-stratose except on margins; margins bistratose, entire or serrulate near the apex, irregularly thickened and recurved at least in distal half; costa stout, percurrent to excurrent, in section with abaxial stereid band; proximal lamina cells elongate-rectangular, distal lamina cells subquadrate to shortrectangular or somewhat irregular in outline, ± incrassate. Specialized asexual reproduction by rounded to pyriform or irregularly-shaped, yellow to orange rhizoidal tubers, to 150 µm. Sexual condition dioicous; perichaetial leaves similar to stem-leaves but with a somewhat longer subula narrowing more abruptly from the base. Seta becoming reddish with age, to 1.5 cm, erect. Capsule erect, dark-brown to reddish-brown, ovoid to cylindrical, symmetric, 1–2 mm, smooth to ± furrowed when dry; operculum obliquely conic-rostrate, blunt, 0.3–0.7 mm; peristome split nearly to the base into 2 segments, brown, densely and finely obliquely-ridged and lightly papillose, 200–250 µm. Spores 11–20 µm, appearing ± smooth.


Phenology: Capsules mature spring–summer (Apr–Jun).
Habitat: Bare, disturbed calcium-free clay, sandy or gravely soil banks, disturbed habitats, especially along roads and trails, and sometimes in cliff crevices
Elevation: low to moderate elevations

Distribution

B.C., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Ala., Ark., Fla., Ga., Ill., Ind., Iowa, Ky., La., Maine, Mass., Mich., Minn., Mo., Nebr., N.Y., Tenn., Tex., Va., Wis., Europe, Asia, Africa, Atlantic Islands (Iceland)

Discussion

When sterile, Ditrichum pusillum is morphologically very similar to D. ambiguum and D. tortuloides. When sporophytes are present, the dense, fine, obliquely striate peristome teeth with weak papillae immediately distinguish D. pusillum from those two species, which have spiculose peristome teeth. The spores of D. pusillum (10–19 µm) are also larger compared to those of D. ambiguum (6–11 µm) and D. tortuloides (9–13 µm). A discussion of the relationships of D. pusillum with both D. ambiguum and D. tortuloides was given by R. R. Ireland and H. Robinson (2001).

Selected References

None.

Lower Taxa

None.

"um" is not declared as a valid unit of measurement for this property.

... more about "Ditrichum pusillum"
forming a marginal border +  and not differentiated +
Rodney D. Seppelt +, Robert R. Ireland Jr. +  and Harold Robinson +
(Hedwig) Hampe +
Didymodon pusillum +
cucullate +
smooth +  and more or less furrowed +
dark-brown;reddish-brown +
cleistocarpous +
ovoid +  and cylindrical +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
percurrent;excurrent +
subpercurrent +
1/6 width of leaf base;1/3 width of leaf base +
shortrectangular +  and isodiametric +
B.C. +, N.B. +, Nfld. and Labr. +, N.S. +, Ont. +, P.E.I. +, Ala. +, Ark. +, Fla. +, Ga. +, Ill. +, Ind. +, Iowa +, Ky. +, La. +, Maine +, Mass. +, Mich. +, Minn. +, Mo. +, Nebr. +, N.Y. +, Tenn. +, Tex. +, Va. +, Wis. +, Europe +, Asia +, Africa +  and Atlantic Islands (Iceland) +
low to moderate elevations +
Bare, disturbed calcium-free clay, sandy or gravely soil banks, disturbed habitats, especially along roads and trails, and sometimes in cliff crevices +
papillose +  and smooth +
dioicous +  and sexual +
subquadrate +  and elongate-rectangular +
flexuose +
acute +, acuminate +, lanceolate +  and linear-lanceolate +
serrulate +  and entire +
denticulate +
blunt +  and conic-rostrate +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.07 cm0.7 mm <br />7.0e-4 m <br />) +
with a longer , broader sheathing base +  and differentiated +
on short branches +  and axillary +
obliquely-ridged +
Capsules mature spring–summer (Apr–Jun). +
filamentous +
yellow;orange +
rounded;pyriform or irregularly-shaped +
flexuose +
elongate +
0 cm0 mm <br />0 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
papillose +
globose +
reaching 2 cm +  and short +
0.4 cm4 mm <br />0.004 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
narrowing +
Ditrichum tortile +, Trichostomum tortile +, Trichostomum tenue +  and Weissia capillacea +
Ditrichum pusillum +
Ditrichum +
species +
yellow;orange +
rounded;pyriform or irregularly-shaped +
specialized +
synoicous +, paroicous +, autoicous +, dioicous +  and sexual +
green +  and yellowish green distally +