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BOTANICAL EXPLORATION IN VENEZUELA - I 111
spike 5-6 mm. wide in fresh condition, up to 10 mm. wide in dried
state with loosely spreading bracts; petals faintly many-nerved,
slightly wavy-margined on top, the rhomboid blade narrowed below
the middle to a cuneate claw; filament inserted somewhat below the
middle near the junction of the claw and the blade of the petal;
staminodia penicillate-plumose above with pale yellow hairs; placentae
basal; ovules numerous (Fig. 16, i-j).
Type in herb. Chi. Nat. Hist. Mus., collected on wet bluffs under
constant spray of swinging waterfall, Ptari-tepuf, along base of eastfacing
high sandstone bluffs, state of Bolivar, alt. 2410-2450 m.,
November 7, 1944, Julian A. Steyermark 59919.
Xyris ptariana belongs to the same group of species as X. Tatei
Malme and X. witsenioides Oliver and is intermediate between these
two. At one end of the series stands X. witsenioides, while at the
other end is X. Tatei, By broadening the leaves and enlarging and
elongating the sheaths and scapes of X. witsenioides, a condition,
more or less like that found in X. ptariana is reached, and, by continuing
one step further, again widening the leaves and scapes of
X. ptariana, the state of X. Tatei is reached. Xyris ptariana has
somewhat larger heads and broader leaves and scapes than has
X. witsenioides, but narrower leaves and scapes than X. Tatei*
Like X. Tatei, to which X. ptariana is most closely related, the
tip of the leaf is prominently incurved-falcate and obtusish, whereas
in X. witsenioides it is scarcely or not at all falcate and more gradually
narrowed to an acute or acuminate apex. In X. ptariana, however,
the lower part of the scape is angled on one side, as in X. witsenioides,
rather than bicostate and biangulate throughout, as in X. Tatei.
In A!, ptariana the keel of the lateral sepal is somewhat less scabrid
than in X. witsenioides. The most conspicuous characteristic of
X. ptariana, however, is the ligule, which is typically recurvedrevolute;
in X. witsenioides the ligule is produced upwards and erect
or straight or protrudes slightly as a small or elongated structure,
whereas in X. Tatei it is spreading-squarrose at the tip. This is
seen best developed, in the species mentioned, on the sheaths of the
uppermost and youngest leaves.
Xyris scabridula Steyermark, sp. nov.
Caespitosa; foliis rigid is coriaceis, flexuosis vel nonnihil laxe
spiraliter tortulis, subcomplanatis vel subteretibus, profunde sulcatis,
glabris, quara scapis multo brevioribus, 6-12 cm. longis, 1-1.5 mm.
latis, aciebus subobtusis; vagina scabridula, inferne fusca nitida;
scapis atro-viridibus rectis vel nonnihil flexuosis laxe tortulis, subteretibus,
subtiliter sulcato-nervatis, 19-26 cm. longis, 0.75-1 mm.
latis; vagina basali purpurea, 6-7 cm. longa, nitida; spicis paucifloris,
ovoideis, 6-7 mm. longis, 3.5-4 mm. crassis; bracteis coriaceis,
integerrimis, adpressis fuscis concoloribus, infimis sterilibus
late oblongis, 3 mm. longis, apice rotundatis, intermediis superioribusque
late oblongis, 5-6 mm. longis, 3-4 mm. latis, apice rotundatis,