hydathode


Also found in: Dictionary, Thesaurus, Medical, Wikipedia.

hydathode

[′hīd·ə‚thōd]
(botany)
An opening of the epidermis of higher plants specialized for exudation of water.
References in periodicals archive ?
5 mm apart, uniting to a marginal commissural vein, set at 50-55[degrees] to costae; hydathodes lacking; costae abaxially and adaxially with scales irregularly divided to amorphous, 0.
1 mm wide, spherical, shiny, yellowish to orangish, sessile to stalked; basal basiscopic segment of more distal pinnules becoming decurrent and adnate to the pinna rachises, the vein supplying the segment springing from the pinna rachis instead of the costule; hydathodes (enlarged vein ends) present adaxially; indusia absent or (less commonly) present, circular, brown, firm, in some species minute and fugacious; x=41.
2E, F), the abaxial surface of the lamina also provided with scattered simple and branched clavate hairs; stomata not visible; hydathodes present, small and inconspicuous; sori 1-3 per segment, confluent at maturity, with setiform hairs like those of the laminae (Fig.
Lehnert 368), but never trapezoid; rarely few ciliform hairs scattered along the segment margins; hydathodes present (Fig.
3D, E), or obscurely so abaxially in dried specimens; segments glabrous except for hairs in sori; margins without hairs; hydathodes present.
It is characterized by the lack or poor development of hydathodes (vs.
Other species with absent or weakly developed hydathodes (M.
7 mm; costae stramineous, raised on both sides, glabrous; laminar tissue chartaceous, glabrous, drying olive green, slightly paler abaxially than adaxially; veins mostly 1-forked, impressed adaxially, raised abaxially, ending in small hydathodes.
5 mm, loosely arranged, lanceolate, tan, ciliate; veins simple, adaxially immersed in leaf tissue, abaxially slightly raised and slightly paler than the laminar tissue, ending in small hydathodes.
2 mm, lanceolate to oblong-lanceolate, appressed to slightly spreading, flaccid, translucent, orangish brown, with finely dentate margins; costae pale brown, deeply sunken adaxially and strongly raised abaxially, moderately scaly, the scales similar to those on rachis but somewhat smaller and relatively broader; laminar tissue coriaceous, drying dark olive adaxially and paler brown abaxially, glabrous; veins mostly simple, rarely 1-forked, impressed on both sides, abaxially conspicuously darker than the laminar tissue, ending in small hydathodes.
2-1 mm long, orange; costae stramineous, slightly raised on both sides, basally with a few scales resembling the rachis scales; laminar tissue chartaceous, glabrous, drying olive green, slightly pale abaxially than adaxially; veins mostly 1-forked, impressed adaxially, raised abaxially, ending in small hydathodes.
0 mm, (7)10-14(20) pairs, linear, ascending, the bases adnate, the apices rounded to acute, the pinna margins crenate or minutely notched on smaller pinnae, the basal pinnae sometimes with a basal constriction caused by the acroscopic and basiscopic margins folding toward the abaxial side, the acroscopic margin provided with a dark sunken nectary, at least on basal pinnae; adaxial lamina surfaces glabrous, hydathodes present, sunken, not white-encrusted; abaxial lamina surfaces densely scaly, the scales 0.