Henry's Sphagnum

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.

Plants moderate-sized to robust, capitulum typically flat, ± 5-radiate and with terminal bud slightly visible; green, pale green, to pale pinkish brown tinged with brown to reddish brown; forming carpets or low hummocks. Stems pale green to brown; superficial cortical layer with spiral reinforcing fibrils clearly visible, usually 4 or more pores per cell, comb-fibrils lacking on onterior wall. Stem leaves to 1.9 × 1 mm; rarely hemiisophyllous; hyaline cells non-ornamented, nonseptate or septate. Branches ± tapering to a point, leaves spreading to moderately imbricate. Branch 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. Branch leaves 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. Sexual condition dioicous. Capsule with numerous pseudostomata. Spores 24-29 µm; surface finely papillose to nearly smooth.

Sphagnum henryense var. bartlettii Warnstorf

Sphagnum henryense Warnst. Hedwigia 39 : 107. 1900 Plants fairly robust, pale-green. Wood-cylinder brown; cortical cells of the stem in 3 layers, their inner walls reinforced by fibril-bands, the outer cells generally quadrilateral, seldom longer than broad, each with 2-5 rounded pores : stem-leaves large, lingulate-spatulate, their hyaline cells generally not divided, somewhat fibrillose, the membrane largely resorbed on the outer surface: branches in fascicles of 4 or 5, 2 spreading, their cortical cells in a single layer, with prominent fibril-bands, the outer wall sometimes showing a large pore in the upper end: branch-leaves spreading, broadly ovate, denticulate; hyaline cells fibrillose, rhomboidal, 6-8 times as long as wide at the base, gradually shorter above, on the inner surface with a few ringed pores in the corners of the cells in the apical part of the leaf, the sideregions with rather large rounded pores in the middle portion of the cell, in the marginal row of cells sometimes very numerous (up to 12) in 2 rows, on the outer surface with very numerous, small, elliptic pores along the commissures, 5-20 per cell, with single large membrane-gaps in the apical cells; chlorophyl-cells narrowly triangular in section with the base exposed on the inner surface, the lumen of similar shape ; inner surface of hyaline cells where overlying chlorophyl-cells beset with a net-work of prominently projecting ridges, especially in the lower part of the leaf; hyaline cells convex on the outer surface, up to one fourth of the diameter of the cell or slightly more; resorption-furrow present. Antheridia and archegonia unknown.
Type locality: Cape Henry, Virginia.
Distribution: Delaware, Virginia, Georgia, and Louisiana.