Trichiaceae=

_A._ Capillitium threads long, generally united to
form a loose net, centrally attached.

_a._ Sculpture spiral 1. _Hemitrichia_

_b._ Sculpture reticulate 2. _Calonema_

_B._ Capillitial threads shorter, entirely free,
though sometimes branched.

_a._ Threads, elaters, marked by spiral bands 3. _Trichia_

_b._ Sculpture irregular or wanting 4. _Oligonema_

=1. Hemitrichia= _Rost._

1829. _Hemiarcyria_ Fries, _Syst. Myc._, III., p. 183 in part.
1873. _Hemitrichia_ Rost., _Versuch_, p. 14.

Capillitium a tangled net of more or less branching and anastomosing
fibres centrally attached; the sculpture regular, of conspicuous
spirally winding bands or ridges; habit and color various.

The species here associated are intermediate between _Arcyria_ and
_Trichia_, resembling the former in the capillitial net and the latter
in thread-sculpture. Fries applied the name _Hemiarcyrieae_ to a group
of trichias so-called, citing _H. rubiformis_ as the first. In his
_Versuch_ Rostafinski wrote _Hemitrichia_ and afterward _Hemiarcyria_ in
the _Monograph_. Massee combines the genera _Arcyria_ and _Hemiarcyria_
under the former name.

=Key to the Species of Hemitrichia=

_A._ Plasmodiocarpous

_a._ Plasmodiocarp net-like, yellow 1. _H. serpula_

_b._ Imperfectly plasmodiocarpous, brown 2. _H. karstenii_

_B._ Sporangia all distinct.

_a._ Sessile; very short stalked

i. Peridium hyaline, iridescent 3. _H. ovata_

ii. Peridium opaque 10. _H. montana_

_b._ Stipitate, generally distinctly so; sometimes
nearly sessile.

i. Yellow or ochraceous.

O Stalk hollow.

+ Small, 1/2 mm., iridescent 6. _H. leiocarpa_

++ Larger, 1 mm., smooth but not iridescent

1. Free ends more or less abundant 8. _H. clavata_

2. Free ends none 9. _H. stipitata_

OO Stalk solid 7. _H. intorta_

ii. Not yellow.

O Ruby red 4. _H. vesparium_

OO Copper-colored 5. _H. stipata_

1. HEMITRICHIA SERPULA (_Scop._) _Rost._