Hydathodes


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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Hydathodes

 

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.

O. N. CHISTIAKOVA

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
hydathodes resisting the pull of gravity (Crafts and Broyer, 1938;
why such local pressures in the stem and epithem cells of hydathodes
Keywords: macrophytes, Fabaceae, hydathode trichome.
Multicellular trichomes are present on the petiole of all evaluated species, classified in four types according to their shape and structure: hydathode trichome (Figure 2A), long cone-shaped trichome (Figure 2B), bulb-like base trichome (Figure 2C), and short cone-shaped trichome (Figure 2D), with distinct distribution among the species, and easily differentiated under SEM (Figure 2E-G).
1 mm aptot, diverging at 65-80[grados] from costa; hydathodes absent; fertile fronds 22-32 cm long; stipes ca.
simple), 1-1.5 mm apart, diverging at 80[grados] from costa; hydathodes absent; fertile fronds not seen.
0.2 mm, linear-lanceolate to subulate, dark-brown, dispersed, marginally entire; blades 9-22 x 3.0-5.8 cm, chartaceous, lanceolate to oblong-elliptic, basically obtuse to truncate, apically acuminate to cuspidate; blade scales 0.7-1.2 x 0.1-0.3 mm, linear to subulate, dark-brown, dispersed, marginally entire, only on blade margin; veins evident, 1-2-forked, 1-1.5 mm apart, diverging at 65-75[grados] from costa; hydathodes absent; fertile fronds 17-28 cm long; stipes 3/5-3/4 the frond length; fertile blades 4.5-10.5 x 1.3-2.8 cm, lanceolate, basically obtuse to truncate, apically acute; intersporangial scales absent.
0.1-0.2 mm, linear to subulate, dark brown, dispersed, marginally entire; blades 1431 x 3.1-5.4 cm, narrowly elliptic to oblong-elliptic, subcoriaceous, basically cuneate, apically acute to cuspidate; blade scales 1-2 x 0.1-0.3 mm, linear to subulate, dark brown to atropurpureous, marginally entire, only on blade margin and rarely on base of costa, dispersed of absent; few evident veins, simple or 1-forked, 1-2 mm apart, diverging at 60-75[grados] from costa; hydathodes absent; fertile fronds 30-45 cm long; stipes 3/5-4/5 the frond length; fertile blades 10.5-17 x 2.6-3.2 cm, lanceolate to elliptic, basically cuneate to obtuse, apically acute to acuminate; interporangial scales absent.
80[degrees] angle from costa; hydathodes absent; fertile fronds 38-44 cm long; stipes 1/3-3/5 of the frond length; fertile blades 20-25 x 0.6-1.1 cm, linear, basically cuneate to obtuse, apically acute; intersporangial scales not seen.
2-3 mm apart, diverging at 70-80[degrees] angle from costa; hydathodes evident, dark brown to blackish; fertile fronds 37-55 cm long; stipes 3/4-4/5 of the frond length; stipe scales 1-3 x 0.3-0.7 mm, ovate to lanceolate, blackish, peltate, marginally dentate; fertile blades 10-18 x 1.8-2.8 cm, lanceolate, basically cuneate to obtuse, apeically acuminate; intersporangial scales ca.
hydathodes. Since this coloration is produced only with the metal