Sphagnum recurvum
Sphagnum henryense
recurved sphagnum
Henry's sphagnum
pale green to yellowish;
superficial cortex of 2 layers of enlarged, thin-walled and well differentiated cells.;
stem leaves triangular, triangular-lingulate to lingulate, more than 0.8 mm, appressed, apex obtuse to broadly obtuse, erose to fimbriate;
hyaline cells efibrillose and nonseptate.
leaves to 1.9 × 1 mm; rarely hemiisophyllous;
hyaline cells non-ornamented, nonseptate or septate.
straight and often tapering, often 5-ranked, leaves not much elongate at distal end of branches.
± tapering to a point, leaves spreading to moderately imbricate.
ovate-lanceolate, 1.4–2 mm, straight; slightly undulate and sharply recurved;
margins entire;
hyaline cells on convex surface with 1 pore per cell at cell apex, concave surface with round wall thinnings in the cell ends and angles; chlorophyllous cells triangular in transverse section and well-enclosed on concave surface.
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.
with numerous pseudostomata.
22–28 µm;
papillose on both surfaces;
proximal laesura more than 0.5 spore radius.
24–29 µm;
surface finely papillose to nearly smooth.
fascicles with 2 spreading and 2 pendent branches.;
branch stems green, cortex enlarged with conspicuous retort cells.
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 recurvum
Sphagnum henryense
Sporophytes in Sphagnum recurvum are uncommon. This species is found exclusively in the New World. It has several strong characters that distinguish it from S. flexuosum, and the opinion of H. A. Crum (1997) that the two species are synonymous is rejected. See discussion under 30. S. flexuosum.
(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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