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Possible Hymenoscyphus fraxineus
B Shelbourne,
02-06-2024 15:25
• Section Scutuloidiae, stroma-leaves group: Spores, excipulum, habitat and macro.
• H. fraxineus: Phenology, large apothecium diameter, habitat, croziers, spore size.
Habitat: On overwintered, blackened, stromatised? twigs with < 5mm diameter, possibly rachises from Fraxinus excelsior, on the floor, some lightly buried, damp and shady area under trees, small streams in sight, mixed deciduous woodland - NVC community W8a (Fraxinus excelsior - Acer campestre - Mercurialis perennis woodland and Primula vulgaris - Glechoma hederacea subcommunity), Lower Weald, England, late May, after rain.
Apothecia: Apparently several hundred in sight and < 10 on each twig, scutellate, whitish-cream, slightly glittering, reddish-brown with age or trauma, diameterdiameter <= ~7.5 mm, cyathiform and eventually discoid, stipitate, opaque in maturity, appears erumpent, firm-gelatinous texture; margin distinct, round and often slightly lobate in maturity, more raised until mature, more whitish; disc concave until maturity then flat to slightly convex; stipe developing early, length varying - apparently longer if more submerged or buried, usually sharply obconical, brownish-orange around the base in maturity.
Associates: Mycena cf, tenerrima on other small twigs, large patch of Helvella crispa nearby.
Storage and methods: Stored overnight in a fridge, two central sections taken from a large, mature-looking apothecium, mounted in water, IKI added to water mount, then KOH+CR added, some pressure applied to separate the cells of the hymenium (croziers were difficult to view clearly).
Asci: Cylindrical-clavate, croziers, IKI – strongly bb, hymenoscyphus-type (mostly lower ring showing), apex rounded to conical-truncate, few discharging.
Vital mature: ~105-120 x 10-11 um, mildly clavate, apex rounded-conical, 1-3-seriate, obliquely arranged,
Dead: ~90-100 x 5-8 um, more cylindrical, apex conical-truncate, thickening ~2-4 um, 1-2-seriate
Discharged: Apparently a large poricidal collar-like opening, with thickening not reverting, some with a little amyloid material remaining at the apex.
Spores: Narrow ellipsoid to scutuloid (heteropolar with apex hooked and base rounded acute), none septating, multiguttulate with 3-6 medium LBs and several smaller ones, larger LBs ~1.3-3.5 um, OCI 4-5, LBs very sensitive and quickly deforming and coalescing, apparently a single nucleus in the centre.
Vital mature spores measured in water or mature asci: (16.9) 17.2 - 21.2 (21.5) × (4.1) 4.5 - 5 µm, Q = (3.4) 3.5 - 4.5 (4.8), N = 6, mean = 18.9 × 4.7 µm, Q mean = 4.
Paraphyses: Narrow cylindrical, apparently multiseptate, many smallish VBs in the apical part, strongly refractive, dextrinoid, branching and some anastomosis observed close to the base.
Ectal excipulum: Thin ochraceous exudate, textura prismatica with larger cells at the surface and textura porrecta underneath, hyaline; cortical cells hypha-like, with VBs, forming a network on the surface, dextrinoid.
Medullary excipulum: Hyaline, textura intricata, appears dense but easily separated, occasional singular hyaline crystals in the stipe (base not observed).
Basal attachment: Not observed.
Hans-Otto Baral,
02-06-2024 16:41
Re : Possible Hymenoscyphus fraxineus
Surely these are Frax. petioles and H. fraxineus. A good idea to look for it. Some 10 years ago the forest floor was covered with millions. In the past years saw it more sporadically.