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The discharge of water from a plant surface, especially from a hydathode.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the exudation of water droplets by plant leaves, occurring when more water is absorbed by the roots than is evaporated by the leaves. It is observed mainly at night, in the early morning, or when plants are placed in a humid atmosphere; it is often observed in young sprouts, such as those of grains, whose root-system development overtakes the development of the evaporative surfaces of their leaves. The drops of water are secreted through water stomata under the action of root pressure, by the force of water pressing into the stems and leaves. Guttation is a physiological process connected with the life processes of the plant; if wheat sprouts are placed under a cone inside of which there is chloroform vapor, guttation ceases. Secretions of guttation always contain a number of mineral substances. Evidently guttation rids the plant of excess salts, mainly calcium.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The patient was evaluated by a dermatologist and was subsequently diagnosed with guttate psoriasis.
ASO titres were positive in 10% of cases and were found to be positive in patients of guttate psoriasis only.
He found guttate psoriasis, mucosal involvement and psoriatic erythroderma to be uncommon.
Plaque psoriasis was the most common type of psoriasis, accounting for 85.1% of patients, followed by guttate psoriasis (2.9%), erythrodermic psoriasis (1.7%), and pustular psoriasis (1.0%).
Patients on systemic anti-psoriatic drugs and/or systemic antibiotics currently and minimum within previous15 days from interviewing were excluded.Study procedure63 recruited psoriasis patients were allocated to one of five groups: 1a acute guttate psoriasis (no psoriasis present when eruption began) [n=15]; 1b guttate flare of chronic psoriasis (n=14]; 2a chronic plaque psoriasis (including scalp psoriasis) [n=26]; 2b sudden exacerbation/ deterioration of chronic plaque psoriasis (n=7);3 Other types of psoriasis (small plaque/atypical guttate/ pustular/ inverse psoriasis) [n=1].
Many dermatoses could be considered in the differential diagnosis of DHK including stucco keratosis, verruca plana, lichen nitidus, Darier's disease, and guttate psoriasis.
Guttate psoriasis is a distinctive acute form of psoriasis, and typically erupts explosively over large areas of the skin surface, usually 1-2 weeks after an episode of acute tonsillitis or pharyngitis.
Several clinical variants of disease have been described, namely, guttate psoriasis, erythrodermic psoriasis, and pustular psoriasis, with chronic plaque psoriasis vulgaris accounting for more than 90% of cases [2-4].
Patients without All patients PsA Patients with PsA Type of Psoriasis (N = 197) (N=102) (N=95) Chronic plaque 181 (91.9%) 90 (88.2%) 91 (95.8%) Pustular 2 (1%) 1 (1%) 1 (1.1%) Palmoplantar 33 (16.8%) 19 (18.6%) 14 (14.7%) Flexural 13 (6.6%) 8 (7.8%) 5 (5.8%) Guttate 32 (16.2%) 13 (12.7%) 19 (20%) Erythrodermic 5 (2.5%) 2 (2%) 3 (3.2%) Type of Psoriasis P Value Chronic plaque 0.05 Pustular 0.96 Palmoplantar 0.53 Flexural 0.46 Guttate 0.16 Erythrodermic 0.59 Table 3: Morphologic features of nail changes.
Psoriasis has four major clinical phenotypes, which are distinguished by the morphological characteristics of their lesions: (i) psoriasis vulgaris, (ii) guttate psoriasis, (iii) pustular psoriasis, and (iv) erythrodermic psoriasis [20].
Pigmentation may be guttate, confetti-like pigmented macules, linear, or in largecircular macules.