46
Holm,
SciapHilous plant-types.
rich in chlorophyll, the intercellular spaces narrow, long, parallel
with the surface. Mestome-strands embedded in the chlorenchyma;
mechanical tissues absent.
Goodyera pubescens R . B r .
Structure bifacial; cuticle thick and wrinkled on both faces,
especially above and beneath the midrib; epidermis thickwalled
on both faces of the blade, especially beneath the midrib; ventral
epidermis with large lumen, almost papillose; stomata level with
epidermis, confined to the dorsal face. Chlorenchyma of one
layer of short, plump palisades covering a very open pneumatic
tissue of five to six strata of roundish to oblong cells, frequently
with wide lacunae, and with large cells containing raphides; the
chlorenchyma is rich in chlorophyll except above the veins. Midrib
as well as the other veins embedded in the chlorenchyma, surro­
unded by green parenchyma-sheaths; mechanical tissues absent.
Aplectrum hyemale (Muehl.) Torr.
Structure bifacial, so far as concerns the chlorenchyma;
cuticle thin and smooth; epidermis is thickwalled on both faces
of the blade, the lateral cell-walls straight, not undulate, and
very porose; thickwalled papillae abound on the upper face,
covering the stereome; small, clavate hairs of three to four cells
occur on the dorsal face; stomata almost equally distributed on
both faces; they are slightly raised, the air-chamber wide, but
shallow. Chlorenchyma of two layers of short palisades covering
a relatively compact, pneumatic tissue of four strata with many
raphide-cells. Stereome very thick-walled as projecting strands
covering the mestome-strands on both faces, or only the leptomeside in the finer veins; large groups of colorless, thinwalled paren­
chyma accompany the hadrome-side of the stronger veins, notably
the midrib.
Tipularia discolor (Pursh) Nutt.
Structure bifacial; cuticle granular on both faces of the blade;
epidermis with the outer cell-wall very thick on both faces; stomata
confined to the dorsal face, slightly raised; clavate hairs like those
of Aplectrum occur on the lower face. Chlorenchyma of two strata
of typical palisades with many raphide-cells; pneumatic tissue
of four compact strata of roundish cells, beside large cells with
raphides. Midrib and some of the thicker veins with small strands
of hypodermal collenchyma on the leptome-side; there is no
thinwalled parenchyma around the mestome-strands, and no
stereome either.
Corallorrhiza odontorhiza Nutt.
The long, tubular leaves of the flowering stem contain no
chlorophyll. Structure unifacial; cuticle smooth; epidermis slightly
thick-walled on the dorsal face, thin-walled on the ventral; some