Sphagnum steerei
Sphagnum henryense
steere's sphagnum
Henry's sphagnum
leaves to 1.2 × 0.8 mm; rarely hemiisophyllous;
hyaline cells mostly nonseptate, comb-lamellae usually absent, but sometimes weak.
leaves to 1.9 × 1 mm; rarely hemiisophyllous;
hyaline cells non-ornamented, nonseptate or septate.
short and blunt-tipped, leaves spreading.
± tapering to a point, leaves spreading to moderately imbricate.
ovate to ovate-elliptical, 1.6–2.2 × 1 mm;
hyaline cells on proximal half of convex surface with round to elliptic pores along the commissures;
comb-lamellae on hyaline cell wall where overlying chlorophyllous cells; chlorophyllous cells broadly triangular in transverse section and well-enclosed on convex surface, end wall not thickened.
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.
dioicous.
unknown.
with numerous pseudostomata.
unknown.
24–29 µm;
surface finely papillose to nearly smooth.
fascicles with 2 spreading and 1 pendent branch.;
branch stems with hyaline cells non-ornamented, no or weak funnel-like projections on the end walls of cortical cells, cortical cell walls usually with large round pores.
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.
Sphagnum steerei
Sphagnum henryense
Sphagnum steerei is usually easily recognized in the field by its dense growth habit and dark brown color. Its ecology is somewhat unclear due to taxonomic confusion with S. imbricatum in the strict sense and S. austinii (R. E. Andrus 1987). The latter is the only species in the imbricatum complex that occurs where S. steerei does. Contrary to the view of H. A. Crum (1997), S. steerei is quite distinct from S. affine and S. austinii. There is no range overlap with either of those species and the macroscopic appearance is also quite different.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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