“Leaf-gall on under surface, having the form of a much depressed
inverted cone, attached by its apex, and with the free base surrounded
by a conspicuous fringe. 3-4 mm. high, 4-5 mm. in diameter. Green to
light yellow-green. Huron, July 25. Quite rare and I believe hitherto
unreported.” Sears.
The author has collected this interesting gall at Gypsum, Ohio, in
August. Many of them measured 5 mm., not including the radiate,
bract-like processes borne on the flaring rim of the gall. The galls
bear an evanescent thin disk of tissue on the distal, central region,
which is clear brown in color and bears erect scattered trichomes. The
underlying surface of the gall or the outer convex part is perfectly
smooth. The origin of the apical, brown disk is problematical; from the
material at hand it appeared as if the rim of the gall had developed by
pushing out beneath the original apical tissue. After the disk falls,
only a minute dark spot marks the apex of the gall. The surface of the
under half of the gall, below the flaring, lacerate rim, is more or
less pubescent.
Chamber comparatively large; walls thin.
This very striking gall has thus far only been collected by Mr. Sears
and myself, both times in northern Ohio and occurring on _H. ovata_.
Some specimens, all occurring on the same leaf varied in that they were
not so depressed (almost sub-hemispheric) and had the rim strongly
inturned against the very convex distal half of the gall.
Sears, Ohio Nat. 15:380. 1914.