214 American Midland Naturalist Monograph No. 6 



11. Helodium (Sullivant) Warnstorf 

 (Elodtium (Sullivant) Warnstorf) 



Autoicous or rarely dioicous: more or less robust, in deep, soft, slightly 

 lustrous, green to yellowish-green or sometimes brownish tufts: stems elliptic 

 in cross-section, without central strand, mostly simple, thickly-foliate, some- 

 what distichously pinnate; branchlets filiform; paraphyses small, branched, 

 numerous; leaves all similar, when dry appressed, when moist erect-spreading, 

 or erect, concave, with a dorsally projecting main plication; stem-leaves from a 

 narrowed base suddenly lance-ovate, acuminate, the margin almost wholly 

 revolute, mostly entire, sometimes apically serrate; costa incomplete, mostly 

 weak; cells pellucid, elongate-hexagonal to almost linear, smooth or unipapil- 

 late over the lumen or in the cell-angle, the basal cells laxly rectangular; 

 branch-leaves smaller; perichaetial leaves erect, pale, plicate, delicate, narrowly 

 acuminate, incompletely costate: seta 2-5 cm long, smooth; capsule inclined 

 to horizontal, oblong-cylindric, brown, more or less arcuate; annulus revoluble; 

 peristome-teeth broadly lance-subulate, yellow, basally confluent, transversely 

 striate, apically almost smooth, hyaline-bordered, high-trabeculate, the plates 

 numerous, and often forked or with transverse walls; inner peristome yellowish, 

 almost smooth, with high basal membrane, carinate; segments as long as teeth, 

 lance-subulate, entire or very narrowly carinately split, cilia 3, complete, deli- 

 cate, smooth; lid convex-conic, acute; calyptra cucullate, glabrous; spores about 

 .010-.016 (-.024) mm. 



A genus of five species, at least one of these in our region.* 



1. Helodium paludosum (Sullivant) Austin 

 {Hypnum paludosum Sullivant; Thuidium paludosum Jaeger and Sauerbeck) 



Plate XL 



Yellowish-green, irregularly pinnate: primary stems creeping, branchlets 

 distichous, unequal: stem leaves somewhat rigid, about 1-1.5 mm long, erect- 

 spreading to somewhat appressed, lance-oblong, acuminate, somewhat cordate 

 at base, concave below, reflexed on the borders, smooth on both faces, at the 

 base bearing 1 to 3 paraphyllose branched filaments, the base decurrent, plicate- 

 striate; costa sub-percurrent; median leaf-cells shortly linear-oblong to linear- 

 rhomboid, usually smooth, sometimes dorsally lightly papillose at the distal 

 end; stems and branches vvith numerous filamentous and branched paraphyllia; 

 branch-leaves narrower, smaller, usually 0.6-0.8 mm long; inner perichaetial 

 leaves oblong, gradually slenderly acuminate, up to 3 mm long, longitudinally 

 plicate: -eta about 1.5-3 cm long, slender, red-castaneous, dextrorse above; 

 capsule oblong-r\'Iindric, curved, strongly inclined to almost horizontal, about 

 3:1, the urn about 3-3.5 mm long; lid conic, apiculate; peristome normally 



* Helodium Blandowii (Weber & Mobr) Warnstorf, is larger than paludosum, 

 having stems up to 10 cm longi and very regularly pinnate; the stem-leaves quickly nar- 

 row to a somewhat clasping base bearing paraphyllose appendages; leaf-cells distinctly 

 papillose dorsally at the distal end. — On wet marshy ground, Eurasia, and from New 

 Jersey, Ohio, and Colorado northwards. 



