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Herbarium — Part 12

The genus was named for Professor D. F. Pott, a German botanist.

Pottia truncata, Fuern., 1. c.

Habit and habitat.--Common in loose bright-green tufts in fields and gardens and along hedge-rows.

Name.--The specific name is the Latin truncata, cut off squarely, and refers to the abrupt summit of the spore-case which appears as if it had been sliced off.

Plant (gametophyte).--Small, 1/4 of an inch high and simple, or longer and branching.

Leaves.--Long-oval with the narrow end attached to the stem, concave, smooth; apex taper-pointed, tipped with a sharp point; margin flat; vein extending below or beyond the apex.

Habit of flowering.--Male and female flowers on the same plant (monoicous).

Veil (calyptra).--Split on one side, smooth.

Spore-case.--Egg-shaped, broad end up (truncate).

Pedicel.--Short, red.

Lid (operculum).--Plano-convex with an oblique beak, falling with the columella attached.

Teeth (peristome).--None.

Spores.--Brown, mature in fall and winter.

Distribution.--North America, Europe, Asia.

Genus DITRICHUM, Timm, (1788)

LEPTOTRICHUM, Hampe, (1842)

The species of this genus are smooth and glossy plants growing in pale yellow-green tufts on soil or on rocks. The plants are dwarf, or tall and slender with lance-shaped, long-pointed leaves, and oval or cylindrical, erect spore-cases on long and straight, rarely flexuous, pedicels.

The peristome has a compound annulus, and a single row of purple teeth cleft to the base into two slender, cross-barred segments, which have suggested the name of the genus.

The generic name Leptotrichum, used by some for the genus, from narrow, and a hair, has been shown by Hampe to be untenable, having previously been given to a genus of fungi. It has been replaced by Ditrichum, from two, and a hair. This name has also the right of priority,

There are seventy-two species in all, seventeen in North America.

Ditrichum pallidum, Leptotrichum pallidum, Hampe, 1. c.--See Colour Plate XIV.

Habit and habitat.--Common in loose tufts, pale or yellow-green, on bare sandy or clay-soil, in fields or by roadsides.

Name.--The specific name pallidum, pale, refers to the colour.

Plant (gametophyte).--Slender, erect.

Leaves.--Open, erect, spreading or curved to one side, lance-shaped at base and prolonged to an awl-shaped apex; vein extending beyond the apex and distinctly toothed.

Habit of flowering.--Male and female flowers on the same plant (monoicous); the male flower-clusters bud-like at the apex of the stem.

Veil (calyptra).--Split up one side.

Spore-case.--Long, egg-shaped, brown.

Pedicel.--Bright yellow, 1 to 2 inches long.

Lid (operculum).--Conical, short-beaked.

Teeth (peristome).--Dark-red, each tooth divided into two unequal forks, free or united by the cross-bars.

Annulus.--Double.

Spores.--Very small, smooth, mature in early spring.

Distribution.--Nearly universal, but not found in Great Britain.