ÆCIDIACEI.

Roestelia, Reb.

Peridium elongated, at length opening by lateral fissures, or a terminal lacerated mouth. Spermogonia on the opposite surface, on the same or on different leaves.

Roestelia cancellata, Reb. Pear-leaf Roestelia; spots yellow, then red, prominent; peridia split to the base into laciniÆ, which remain united at the apex.—On Pear leaves. Not very common. Autumn. (Plate II. figs. 20, 21.)

Roestelia cornuta, Tul. Horn-like Roestelia; spots rusty-brown; peridia cylindrical, slightly curved, yellowish-brown; spores greyish, at length brown.—On the under surface of the leaves of Mountain-Ash. Not common. August. (Plate II. figs. 18, 19.)

Roestelia lacerata, Tul. Lacerated Roestelia; peridia clustered in tufts, brown, elongated, splitting to the base in segments; spores light brown.—On the under surface of the leaves, and on the petioles and fruit of the Hawthorn. Not uncommon. May to July. (Plate II. figs. 22, 26.)

Peridium elongated, at length bursting irregularly. Spermogonia scattered, conspicuous.

Peridermium Pini, Chev.; peridia oblong, scattered, large; spores orange, abundant; spermogonia vernal or autumnal, or both; spermatia large, white.—On leaves and young branches of Scotch Fir. Common in Scotland, occasional in England. Summer. (Plate II. figs. 27, 28.)

Peridermium elatinum, Lk.; simple, immersed; peridia elliptic, pallid; sporidia orange.—On Silver Fir, altering both foliage and ramification. Not common.

Æcidium, Pers.

Peridium seldom elongated, opening by a terminal mouth, surrounded by a fringe of recurved teeth, or when short bursting irregularly. Spores disposed in chains. Spermogonia on the same or the opposite surface, clustered or scattered, central or intermixed.

Sect. I.—Peridia scattered (not collected in tufts or clusters).

Æcidium leucospermum, DC. White-spored Cluster-Cups; spots yellowish; peridia scattered, often covering the whole under surface; spores white, ovate.—On both sides of the leaves of the wood-anemone. Common. June. (Plate I. figs. 4-6.)

Æcidium quadrifidum, DC. Four-lobed Cluster-Cups; spots brownish; peridia scattered, occupying almost the entire under surface; spores brown, subglobose.—On the under side of leaves of Anemone in gardens. (Lobes at the mouth of the peridium not constantly four.) April to May.

Æcidium albescens, Grev. Moschatel Cluster-Cups; leaf blistered, whitish, scattered; peridia white, split into a few large teeth; spores yellowish-white.—On leaves and petioles of Adoxa moschatellina. Not uncommon. April.

Æcidium Epilobii, DC. Willow-herb Cluster-Cups; spots obliterated; peridia scattered, at length oval, wider above; spores orange, at length brown.—On the under side of leaves of Epilobium montanum, E. hirsutum, and E. palustre, rarely on the upper. Common. June to August.

Æcidium Thesii, Desv. Bastard-toadflax Cluster-Cups; spots obliterated; peridia scattered or biseriate; short, cylindrical, margin irregularly toothed, erect; spores yellowish, then dingy.—On Thesium humifusum. Downs near Winchester. July, 1864. Chipstead, Surrey, Oct. 14, 1864. (Plate III. figs. 50, 51.)

Æcidium SoldanellÆ, Hornsch. Soldanella Cluster-Cups; spots obliterated; peridia solitary, scattered over the inferior surface; spores orange.—On the under surface of the leaves of Soldanella alpina.

Æcidium Tragopogonis, Pers. Goatsbeard Cluster-Cups; spots obliterated; peridia scattered, torn, wider above; spores orange, at length black.—On stems, leaves, and involucres of common Goatsbeard. Very common. May to June. (Plate I. figs. 1-3.)

Æcidium EuphorbiÆ, Pers. Spurge Cluster-Cups; spots obliterated, leaf thickened; peridia scattered or crowded, distinct; spores orange.—On the under surface of the leaves of Spurge. Common. May to June.