Please try our next iteration of the Michigan Flora Online here. Beginning on February 1, 2023, michiganflora.net will point to this new site.

The new site offers several benefits over the existing website, including real coordinate mapping, giving a clearer view of the density of documentation as well as more precision about plant distributions and their link to landforms. We will also have the ability to update species pages more regularly, both in terms of new collections and as more existing Michigan specimens are georeferenced. In addition, we have a better photo display, and offer indented keys.

Diphasiastrum

Hybrids between species of Diphasiastrum are apparently fertile. They are intermediate in morphology, but can occasionally occur without one or even both parents. The commonest hybrid is D. ×habereri (House) Holub, between the widespread D. digitatum and D. tristachyum. This is best distinguished by having a relatively shallowly buried horizontal stem but with lower leaves of the branches much less reduced than in D. digitatum. The hybrids D. complanatum × D. tristachyum (D. ×zeilleri (Rouy) Holub) and D. complanatum × D. digitatum (D. ×verecundum A. V. Gilman) are much rarer.

1. Strobili sessile; collected long ago in Keewenaw Co.

D. alpinum

1. Strobili (or groups of strobili) short to long peduncled; widespread.

2. Strobili 1 (–2) on short to elongated, rarely forked peduncles; base of strobilus with a few sporophylls scattered along peduncle; stomata on both leaf surfaces; known only from Chippewa Co.

D. ×sabinifolium

2. Strobili 2–4 on forked peduncles; base of strobilus compact and abruptly distinct from peduncle; stomata on lower leaf surfaces only.

3. Horizontal stems almost always buried ca. 4–10 cm in the soil; ultimate (outermost) branches squarish in cross section, 1–2 mm wide; plants usually blue-green (except in deep shade); lower leaves the same size as the upper.

D. tristachyum

3. Horizontal stems superficial, or slightly buried (< 4 cm) in the litter; ultimate (outermost) branches flat in cross section; 2–4 mm wide; plants not blue-green; lower leaves reduced to a leaf base and a short free appendage.

4. Ultimate branches symmetrically in one plane forming a layered appearance; annual constrictions mostly absent; peduncles of strobili 0.6–1 mm in diameter and staying green until after spore discharge in autumn (Sept. –early Oct.); widespread.

D. digitatum

4. Ultimate branches not evenly layered, giving an irregular appearance; annual constrictions uniformly present; peduncles of strobili 0.4–0.7 mm in diameter and losing green by spore discharge in late summer (late July–early Aug.); Upper Peninsula and northernmost Lower Peninsula south (very rarely) to ca. 44° 30’ N.

D. complanatum

All species found in Diphasiastrum

Diphasiastrum ×sabinifoliumSAVIN-LEAVED CLUBMOSS 
Diphasiastrum alpinumALPINE CLUBMOSS 
Diphasiastrum complanatumGROUND-CEDAR 
Diphasiastrum digitatumGROUND-CEDAR 
Diphasiastrum tristachyumGROUND-CEDAR 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. January 29, 2023. https://michiganflora.net/genus.aspx?id=Diphasiastrum.