Acrochaetium intermedium C. C. Jao

Explanation of plate 11
fee 1'igs. 1-4. Acrochaetiim intermedium Jao, sp. nov. Figure 1, habit drawing of an
adult plant, X84; figure 2, part of the plant, showing the structures of vegetative cells
and bisporangia, X605; ligures 3-4, basal parts of the plants, showing the intra-mem-
branal habit, X605.
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volume 63 plate ti	Acrochaetium intermedium, sp. nov.
(PI. 11, figs. 1-4) *?' ’v... . -
Thallo endophytico, 1-2 mm. alto, cellulis basalibus elongatis, 13-16/i altis,
32-57/* longis, 1-3 filis rhizoideis gigncntibus, longitudine 1- vel 5-cellularibus;
parte inferiore cellulae basalis et filis rhizoideis in vel inter mcmbranum hospi-
tis penetratis; filamentis erectis singulis, a basi ramosis, ramulis secundariis
regulariter secundis, cellulis 8-10/* altis, (26-) 32-64/i longis; cellula terminali
leviter attenuati, crassitudine circa 6.5m; chromatophoro parietali pyrenoideo
centrali instructo; sine pilis; bisporangiis et monosporangiis cylindrico-obo-
voideis vel ovatis, 9-13/* altis, 19-23/* longis, plerumque sessilibus, rarius
pediculo unicellulo, in cellulis ramulorum inferioribus secundis, 2- 6-seriatis,
interdum unilateraliter sparsis in parte superiore filorum principium, cellula
inferiore plerumque longiore quam superiore.
iw6|	jao: eiiodophyceae	243
Plants endophytic, 1 -2 mm. tall; the base consisting of the original spore,
which elongates downward to form a cuneate prolongation, penetrating into
the host plant between or in the cell walls, from the basal cell, or rarely from
the adjoining cell, giving rise to one to three rhizoidial filaments of 1-5 cells
in length, wholly imbedded in cell walls of the host plant, except those rhizoids
which rise from the adjoining cell, the upper part of the basal cell retaining
the original spore form, 13-16/* in diameter, but elongated to 32-57/i; from
each spore a single erect main filament arises, ramifying by numerous long
branches beginning near the basal cell; secondary branches regularly secund,
cells 8-10/i diameter, (26-) 32-64/* long, terminal cells tapering, with a di-
ameter about 6.5/i; chromatophore parietal, a little lobed on both ends, gener-
ally occupying the upper end of the cell, with a prominent central pyrenoid;
hairs absent; bisporangia and monosporangia cylindric-ovate to ovate, 9-13/i
diameter, 19-23/* long, secund, mostly sessile, rarely 1-celled pedicellate,
placed upon the lowermost cells of the branches or branchlets, two to six on
each branch, occasionally also scattered unilaterally on the upper part of the
main filaments; the upper cell of the bisporangium is generally shorter than
the lower.
The writer’s materials are rather past their full maturity. The upper
cells of the bisporangia are mostly empty and only a few bisporangia were
found containing spores in both upper and lower cells. The empty bispor-
angia were commonly divided by a very clear, straight cross wall, espe-
cially when placed upon the lowest articulations of the branches.
These plants have some characteristics of both Acrochaetium Dasyae
Collins and A. opetigerum B^rgesen, but differ from the first in having an
endophytic base, an elongated basal cell (original spore) often with rhizoid-
ial filaments penetrating into the cell wall of the host, greater dimensions
of all cells, and much more abundant branching; from the second in having
the secondary branches regularly secund; and from both in having the
sporangia quite often divided into two cells.
The plants are abundant and mostly grow at the fork of the pinnules
of the host plants, Dasya pedic-ellata C. Ag., rarely on other parts. Collected
from Grassy and Pine Islands, Woods Hole, Massachusetts, Aug. 7, 1934.
Type in C.-C. Jao collections and Herb. Univ. Mich., Woods Hole No. 277.
NEW YORK BOTANICAL GARDEN
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