Xyris montana
Xyridaceae
northern yellow-eyed-grass, xyris de montagne, xyris des montagnes
yellow-eyed-grass family
compact.
in narrow fans, 4–15 cm;
sheaths reddish, soft, papillate;
blade deep green, narrowly linear, 0.8–2(–3) mm wide, smooth, margins smooth to papillate.
alternate, 2-ranked (occasionally many-ranked);
base equitant, sheathing or open, sometimes with ligule or auricles at junction;
blade mostly linear or filiform, flat to variously thickened and/or sulcate [lingulate], margins entire to papillate or scabrous;
venation parallel.
scape sheaths exceeded by leaves;
scapes linear, wiry, terete, (0.25–)0.5–0.8(–1) mm wide, distally with 2–4 ribs, ribs papillate;
spikes broadly to narrowly ellipsoid or ovoid, 4–8 mm;
fertile bracts 3–4(–4.5) mm, margins erose or minutely fimbriolate, sometimes with narrow reddish border, apex very slightly to slightly keeled.
terminal;
scape sheaths proximally tubular, distally open, bladed;
scapes erect, linear to filiform, not bracteate [bracteate];
spikes single [cluster, rarely panicle of spikes], conelike;
bracts chaffy.
lateral sepals slightly exserted, straight, 4.2–4.7 mm, keel scarious, entire or apically lacerate, apex red, narrow, firm;
petals unfolding in morning, blade obovate, 3–4 mm;
staminodes bearded.
bisexual, radially [bilaterally] symmetric;
sepals [2–]3, unequal [equal], outer 2 (lateral sepals) nearly opposite, connivent to variously connate, clasping mature capsule, inner sepal membranous (occasionally similar to others or absent), abcissing as flower opens;
petals 3, equal [unequal], distinct [connate];
stamens 3;
staminodes (0–)3, 2-brachiate, free [adnate to perianth or absent];
anthers 4-sporangiate, 2-locular at anthesis;
pollen monosulcate or inaperturate;
ovaries y superior, 1[–3]-locular;
ovules anatropous;
styles 1, distally 3-branched [simple];
stigmas 3 [1, 3-lobed, capitate, or funnelform].
capsular, mostly loculicidal.
translucent, narrowly ellipsoid, (0.6–)0.7–0.9(–1) mm, finely lined.
[1–6–]15–90 or more, mostly under 2[–4] mm, mostly ridged or lined.
Xyris montana
Xyridaceae
Most or all known populations of this species fall within the boundaries of Wisconsin glaciation. The long stems (a trait not known for other North American species) are a response to the burial of the clump bases in deep sphagnum.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
All North American Xyris increase by axillary buds, and thus the solitary habit is rare, often a result of poor or droughty habitat. A few can be termed annual or short-lived perennials (i.e., X. brevifolia, X. flabelliformis, X. jupicai). Of these only S. jupicai tends to die to the base at the end of a growing season.
In North American Xyris, leaf arrangement is distichous (2-ranked) and equitant (much as it is in Iris), the sheath margins converging at the junction of sheath and blade to form one edge of the leaf blade, with the midzone (or keel) of the sheath making up the other edge (a "unifacial" blade). A few species show some trends toward a spiral arrangement, typically displayed by a bulbous habit (X. caroliniana, X. platylepis, X. scabrifolia, X. tennesseensis, XS. torta). In these species, the leaf sheath is abruptly dilated at the base, imparting a swollen, bulblike aspect to the plant base.
While all All North American Xyris have unifacial leaf blades, some neotropical species do not. In those the latter the sheath margins do not completely converge when passing into the blade, and the blade may have a deep, narrow or broad groove or sulcus adaxially. A tendency toward this is shown in X. baldwiniana and X. isoetifolia.
The staminode in nearly all Xyris is much like a petal, being long-clawed at the base. The staminodial blade is typically 2-lobed, each lobe with a margin of long, moniliform hairs, each hair a chain of tiny cells connected much like a string of beads. Species-by-species taxonomic evaluations of those hairs, particularly SEM studies, have yet to be done. Of the species treated herein, only X. baldwiniana lacks bearded staminodes.
The keys and descriptions below are constructed from study of mature, preferably fruiting specimens. Bracts and sepals tend to grow substantially after flowering, and the measurements of lateral sepals are based on sepals that subtend ripe fruit.
North American Xyris have no nectaries, and the pollen reward is relatively scanty. A few bees and flies are occasional visitors. Usually pollination of these species appears to be by wind or by pollen-feeding insects.
Genera 5, species ca. 300 (1 genus, 21 species in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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