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adaptations in plants for the excretion of tiny droplets of moisture (guttation).

Hydathodes serve for the passive exudation of surplus water through the epidermal pores under the effect of root pressure. They are found primarily in plants with weak transpiration that live in conditions of excessive soil moisture. The hydathodes are located on the apexes of the leaves or on the tips of the laminar denticles. In the majority of plants they are modified stomata whose guard cells never close. The pore is sometimes surrounded by ordinary epidermal cells. Some hydathodes are actively moisture-excreting glandulae.


References in periodicals archive ?
The structure and development of the hydathodes of Spartina townsendii Groves.
3 mm, set 45-90[degrees] to the rachis, each spaced 1-2 times its width, linear-lanceolate, oblong to linear, the bases decurrent basiscopically, straight or nearly so acroscopically, pinna margins entire (sterile) to undulate or slightly crenate (fertile), the apices rounded (sterile) to subacute (fertile); veins free, pinnate, branched once, not visible without transmitted light; hydathodes lacking adaxially; sori brown, round, 8-12(-18) per pinna, medial to submarginal, 0.
and thickening in the tracheids near the hydathodes (Garg et al.
8 mm wide, chartaceous to coriaceous, elliptic, apices rounded, margins recurved when dry, veins barely visible, terminating in hydathodes close to the margins; laminar scales similar to those of the stipes, densely covering both surfaces when young, then glabrescent on the adaxial surface.
1 mm apart, set at 90[degrees] to costae, hydathodes lacking; blades on abaxial surface with minute, brown, stellate scales; costae sulcate until 1/2 the sterile leaf length, with scales oblong-lanceolate, 1-1.
feeoides has been applied commonly for specimens from the Pacific area, the two differ by hydathodes of the adaxial surface frequent in S.
The dryopteroid genera that have hydathodes are Didymochlaena (pers.
Melpomene is characterized by having ventral root insertion, reddish brown clathrate scales with apical and sometimes also marginal gland-like cells, hydathodes without calcareous deposits, and is distinguished from other grammitid genera by having secondary metabolites with a distinctive sweet and spicy odor (Smith and Moran, 1992).
1E, F), without hairs; proximal 1-7 segment pairs markedly smaller than subsequent segments, sometimes the lowermost 1-4 segment pairs auriculiform; stomata sometimes visible as rusty red dots; segment margins without hairs; hydathodes present (Fig.
Sterile fronds to 46 cm long; lamina to 29 cm long, sagittate, ovate-lanceolate to 3-5-lobate, occasionally pentagonal, pedate, usually broadly pinnatilobed, apex acute to acuminate; margin serrate with ascending teeth; hydathodes present.
2 mm, arachnoid, appressed, pale brown; veins simple or 1-forked, adaxially slightly immersed, abaxially slightly raised and slightly paler than the laminar tissue, ending in small hydathodes.