110 NORTH AMERICAN FLORA [VoLuME 7 
DISTRIBUTION : New Hampshire to Washington, southward to Florida and Colorado ; also in 
Europe. 
Exsiccati: Seym. & Earle, Econ. Fungi 44, 486 ; Sydow, Ured. 1/88. 
5. MELAMPSORIDIUM Kileb. Zeits. Pflanzenkr. 9: 21. 1899. 
Cycle of development includes pycnia, aecia, uredinia, and telia, with distinct alter- 
nating phases; heteroecious. Pycnia subcuticular, other sori subepidermal. 
Pycnia flattened-conoidal, without ostiolar filaments. 
Aecia erumpent, subcylindrical. Peridium regularly dehiscent, cells rhomboidal. Aecio- 
spores ellipsoid to globoid; wall colorless, thin, verrucose except one side which is thin- 
ner and smooth. 
Uredinia somewhat erumpent. Peridium firm, dehiscent by central pore ; peridial cells 
isodiametric, those of orifice prolonged into sharp points. Urediniospores borne singly on 
pedicels, ellipsoid ; wall colorless, echinulate, pores indistinct. 
Telia indehiscent, forming evident layers immediately beneath the epidermis. Telio- 
spores oblong or prismatic, one-celled ; wall smooth, slightly colored. 
Type species, Melampsora betulina Tul. (on Betula alba). 
1. Melampsoridium Betulae (Schum.) Arthur. 
Uredo populina pg betulina Pers. Syn. Fung. 219. 1801. 
Uredo Betulae Schum. Enum. Pl. Saell, 2: 228. 1803. 
Uredo ovata Belulae Strauss, Ann. Wett. Ges. 2: 93. 1810. 
Melampsora betulina Tul, Ann. Sci. Nat. IV. 2: 97. 1854, 
Aecidium Laricis Keb, Zeits. Pflanzenkr. 9: 18. 1899. 
Metampsoridium betulinum Kleb. Zeits. Pflanzenkr.9: 21. 1899. 
Peridermium Laricis Arth. & Kern, Bull. Torrey Club 33: 436. 1906. 
O. Pycnia amphigenous, rather numerous, scattered, inconspicuous, subcuticular, pale- 
yellow, flattened conical, 50-65 in diameter by 20-30 high; pycniospores oval, 1.5-2% 
long, abundant. 
I. Aecia from a limited mycelium, hypophyllous, solitary or in rows on one or both 
sides of the midrib, flattened laterally, or subcylindrical, 0.1-0.15 mm. wide, 0.3-1 mm. 
long, by 0.3-0.5 mm. high; peridium light reddish-orange fading to white, rupturing along 
the apical line, peridial cells rhomboidal in longitudinal section, 25-304 long, somewhat 
overlapping, inner wall finely verrucose, transversely striate, 2-3 thick, outer of equal 
thickness, smooth ; aeciospores globoid or broadly ellipsoid, 12-18 by 16-25; wall coler- 
less, rather thin, 1-1.5, closely and evenly verrucose, except a small area on one side 
which is smooth and slightly thinner. 
ON PINACEAE : : ; 
Larix sp. Not yet found in America. 
II. Uredinia hypophyllous, scattered, small, round, less than 0.5 mm. across, reddish- 
yellow, at last somewhat pulverulent; peridium hemispherical, firm, dehiscent by a small 
central orifice, cells polygonal, with outer wall thin, 1-3 4, inner wall thick, 6-8, extended 
at the orifice into long points; urediniospores elongate-elliptical or obovate, sometimes 
clavate, 8-14 by 22-38; wall colorless, thin, less than 1 thick, strongly and sparsely 
echinulate, except apex, which is smooth ; paraphyses rudimentary, thin-walled, fusiform, 
7-11 by 25-35 u. . 
III. Telia hypophyllous, scattered, small, scarcely 0.5 mm. across, often thickly cover- 
ing the surface of the leaf, at first waxy-yellow, becoming brown and finally blackish, in- 
dehiscent; teliospores prismatic in a palisade-like layer beneath the epidermis, 7-16 by 
30-50 #, somewhat rounded at each end; wall nearly colorless, thin, scarcely 1 thick, 
slightly thicker at apex, 1.54, smooth. 
On BETULACEAE: . ; 
Betula glandulosa Michx., Washington. ; 
Betula lutea Michx., Indiana, New Hampshire. 
Betula populifolia Marsh., Massachusetts. 
Betula pumila l,., Massachusetts, Michigan ; Newfoundland. 
TYPE LOCALITY: Island of Zealand, Denmark, on Betula alba. 
DISTRIBUTION: Massachusetts, Indiana and Washington northward into Canada: also in 
Europe and Asia. 
