Sphagnum henryense
Sphagnaceae
Henry's sphagnum
leaves to 1.9 × 1 mm; rarely hemiisophyllous;
hyaline cells non-ornamented, nonseptate or septate.
± tapering to a point, leaves spreading to moderately imbricate.
usually of two distinctly different types;
branch leaves that are normally inrolled and broadest ca. 1/4–1/3 the distance from the base, more or less tapered to a cucullate to involute apex;
stem leaves more or less flat and usually broadest at the base;
both leaf types of a network of hyaline, dead cells and green chlorophyllose cells;
pores and reinforcing fibrils frequent in branch leaf hyaline cells and uncommon in stem leaf hyaline cells.
ovate, to 2.7 × 1 mm;
hyaline cells on convex surface with numerous small round pores along the commissures, cell walls overlying chlorophyll cells often with a network of irregular worm like ridges although they may be lacking; chlorophyllous cells isosceles-triangular to narrowly ovate triangular in transverse section and just enclosed on convex surface,end wall not thickened.
dioicous.
with numerous pseudostomata.
24–29 µm;
surface finely papillose to nearly smooth.
released by explosive opening of operculum.
fascicles with 2 spreading and 2 pendent branches.;
branch stems with hyaline cells non-ornamented; funnel-like projections absent from interior end walls, large round pores on superficial walls.
thallose.
lacking.
consisting of a spherical capsule with pseudostomata on capsule surface, a very short seta, and a foot, exserted on a pseudopodium of gametophyte tissue.
Sphagnum henryense
Sphagnaceae
The typical form of Sphagnum henryense is a large plant with a quite flat capitulum with a small terminal bud. Microscopically, typical material has distinct ridges on the branch leaf hyaline cells and relatively small and round pores on the branch leaf hyaline cell convex surface. Sphagnum palustre, which has the same branch leaf chlorophyll cell cross section, typically has smooth hyaline cell walls and hyaline cell pores that are larger and more elliptical in shape. However, Sphagnum species are plastic phenotypically and it is common to find plants that cannot be reliably assigned to either S. henryense or S. palustre. For example, some species of Sphagnum that are relatively easy to distinguish on other characteristics, such as S. papillosum, S. alaskense and S. affine, may occasionally completely lack any hyaline cell ornamentation or display it in reduced form. Since these can be distinguished on other characters, the species are still readily identifiable, but when S. henryense lacks the ornamentation, there is no other solid character to distinguish it from S. palustre. Thus, although we can find material from both North American coasts that has good ornamentation (R. E. Andrus 1980), there is much other material that looks in other respects like S. henryense but lacks the ornamentation. Barring taxonomy beyond microscopic examination, many collections of henryense/palustre will of necessity not be absolutely identifiable. Where their ranges overlap, mixed stands may often be found. We believe that the species are still good, but accurate delimitation of their distinctive ecologies and ranges will be very problematic.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The sphagnum mosses, or peat mosses, are unique not only morphologically but also ecologically. With their abundant clear cells they can retain up to 25 times their dry weight in water, and a uniquely strong acidifying power permits sphagnum to direct succession wherever conditions are suitable for them to flourish. Much of the earth’s surface with a cool humid climate is dominated, thus, by sphagnum peatlands.
Genus 1, species ca. 285 (89 species in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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