Summary: Features include minute, pitcher-shaped, pendant or erect, white to cream fruiting bodies +/- stem, growth on dead plant remains and dead wood, and microscopic characters including basidia. According to R. Singer, C. capula (Holmsk. ex Fr.) Quel. sensu Donk has spores 5-6 microns wide: similar species with narrower spores are often determined as Calyptella capula sensu Bourdot & Galzin, Reid.
Microscopic: spores (6.4)8-9(10) x 4.0-5.6(6.2) microns, elliptic to oboval, inequilateral, smooth, inamyloid, thin-walled, colorless, with a prominent apiculus; basidia 4-spored, 20-24 x 5-7 microns, clamped, cylindric when young, becoming clavate, subhymenium: hyphae densely interwoven, noninflated, thin-walled, clamped; receptacle pellis: hyphae repent, radiating, noninflated, 2-5 microns in diameter, becoming diverticulate and developing coralloid branches or ends especially at the rim, less diverticulate and becoming more elongated near the pseudostem, thin-walled to slightly thick-walled near pseudostem, trama: hyphae parallel, inflated, clamped, 3.2-16 microns in diameter, walls hyaline to pale gray, inamyloid, (Redhead(35)), spores 6-11 x 3-4.5 microns, ovate, flattened on one side smooth, colorless, apiculate; hairs up to 25 microns long that are sometimes dichotomously branched and acanthophysoid; hymenium formed by tight palisade of basidia 21-25 microns thick, basidia 16-23 x 3.5-8 microns, 4-spored; context of clamped hyphae 2-3 microns in diameter reaching 8 microns in diameter in outer tissues of some specimens, (Cooke), spores 6-9 x 3.5-4.5 microns, elliptic, somewhat flattened on one side, smooth, inamyloid, colorless; basidia 4-spored, 20-25 x 6-8 microns, clavate, with basal clamp connection; cystidia not seen; hyphal system monomitic, hyphae in subhymenium 2-4 microns wide, septa with clamp connections, hyphae in stem and trama up to 15 microns wide, "hyphal ends in the marginal part of the cup sinuous-gnarled with outgrowths", (Breitenbach)
Spore Deposit: white (Buczacki)
Notes: Calyptella capula is found at least in BC, WA, ID, and also AB, MB, NF, ON, FL, IL, LA, MA, MD, NC, NJ, NY, OH, SC, and VA, (Ginns).
Habitat and Range
SIMILAR SPECIES
Calyptella campanula (reported from Ontario) varies in color from sulphur yellow to yellowish white in young stages to pale yellow to ochreous in older stages, and microscopically lacks the grayish walls of the tramal hyphae that characterize C. capula. Its diverticulate hyphae are less well developed. (Redhead(35)). Calyptella griseopallida (reported from Manitoba) is grayish to ochreous and is characterized by a repent covering of mycelial hairs that are generally smooth but occasionally become coralloid at their apices especially near the rim of the receptacle, (Redhead(35)).
Habitat
on senescent stems of Medicago sativa, Lathyrus sp., Lactuca serriola var. integrata, Cirsium arvense, Symphytum officinale, leaves of Carex sp.; in fields, swamps and wet depressions back of coastal dunes, near the ground level, (Redhead(35)), gregarious, without subiculum, on dead wood and herbaceous litter (Cooke), dead wood, dead stems, herbs and grass litter, Carex sp., Cirsium arvense, Eupatorium sp., Foeniculum sp., Lactuca serriola, Lathyrus sp., Medicago sativa, Pelargonium zonale, Pteretis pensylvanica, Symphytum officinale, (Ginns), single to gregarious on dead plant remains and dead wood in damp places, (Breitenbach), summer to fall (Buczacki)