A section of hydathode in the leaf of Primula sinensis (Brockhaus and Efron Encyclopedic Dictionary)
A hydathode is a type of pore, commonly found in vascular plants,[1] that secretes water through pores in the epidermis or leaf margin, typically at the tip of a marginal tooth or serration. Hydathodes occur in the leaves of submerged aquatic plants such as Ranunculus fluitans[2] as well as herbaceous plants of drier habitats such as Campanula rotundifolia.[3] They are connected to the plant vascular system by a vascular bundle. Hydathodes are commonly seen in water lettuce, water hyacinth, rose, balsam, and many other species.
Hydathodes are made of a group of living cells with numerous intercellular spaces filled with water, but few or no chloroplasts, and represent modified bundle-ends. These cells (called epithem cells[4]) open out into one or more sub-epidermal chambers. These, in turn, communicate with the exterior through an open water stoma or open pore. The water stoma structurally resembles an ordinary stoma, but is usually larger and has lost the power of movement.
Hydathodes are involved in the process of guttation, in which positive xylem pressure (due to root pressure) causes liquid to exude from the pores.[5] Some halophytes possess glandular trichomes that actively secrete salt in order to reduce the concentration of cytotoxic inorganic ions in their cytoplasm; this may lead to the formation of a white powdery substance on the surface of the leaf.
Hydathodes are of two types:
passive hydathodes, formed when a leaf vein terminates in an epithem (an area of thin-walled parenchyma).
active hydathodes, formed when epidermal cells lose water actively.
^Anatomy of leaf apical hydathodes in four monocotyledon plants of economic and academic relevance
^Mortlock, C. (1952). "The structure and development of the hydathodes of Ranunculus fluitans Lam". New Phytologist. 51 (2): 129–138. doi:10.1111/j.1469-8137.1952.tb06121.x.
^Stevens, C.J.; Wilson, J; McAllister, H.A. (2012). "Biological Flora of the British Isles: Campanula rotundifolia". Journal of Ecology. 100 (3): 821–839. Bibcode:2012JEcol.100..821S. doi:10.1111/j.1365-2745.2012.01963.x.
^Cutter, E.G. (1978). Plant Anatomy. Part 1. Cells and Tissues. London, U.K.: Edward Arnold. pp. 226–227. ISBN 978-0713126389.
^Taiz, Lincoln; Zeiger, Eduardo (2010). Plant Physiology (5th (International) ed.). Sinauer Associates, Inc. p. 90. ISBN 9780878935659.
A hydathode is a type of pore, commonly found in vascular plants, that secretes water through pores in the epidermis or leaf margin, typically at the...
the intercellular spaces of the hydathode tissue toward the openings in the epidermis. Strictly speaking, such hydathodes are not glands because they are...
up in the plant, and excess water is excreted through pores known as hydathodes. The movement of water out of the leaf stomata sets up a transpiration...
guttation The secretion of liquid water from uninjured plant parts. See hydathode. guttulate Having or appearing to be spotted with oil droplets; of spores...
hairless, oval and opposite, 6 to 25 mm long by 3 to 10 mm wide with a hydathode at the tip. The flowers are small, less than 1 cm in diameter, with 5...
midrib and extend toward the leaf margins. These often terminate in a hydathode, a secretory organ, at the margin. In turn, smaller veins branch from...
In some circumstances, the sap will be forced from the leaf through a hydathode in a phenomenon known as guttation. Root pressure is highest in the morning...
below, flat, lobed and serrated with obtuse teeth that have a tiny white hydathode at the tip. Inflorescences are terminal or in the leaf axils and consist...
also New Zealand Calla Council Leaf Shape Images) The leaves contain hydathodes that result in guttation. Inflorescence: Takes the form of a solitary...
Efron Encyclopedic Dictionary Насекомоядные (Insectivora) A section of hydathode in the leaf of Primula sinensis Aponogeton madagascariensis Coat of arms...
forces some water to exude through special leaf tip or edge structures, hydathodes or water glands, forming drops. Root pressure provides the impetus for...
perennial species with alternate and entire leaves, a single subaxial hydathode and pentamerous obdiplostemous flowers with free petals. Most systematic...
Instead, he believed that extrafloral nectaries were excretory in nature (hydathodes). Their defensive functions were first recognized by the Italian botanist...
long-stalked, rounded to heart-shaped, usually slightly toothed, with prominent hydathodes, and often wither early. Leaves on the flowering stems are long and narrow...
different: The Gunneraceae are a mesophilic herb (often oversized), and the hydathodes are well developed and secrete mucilage or perhaps a resinous coating...
with its margin lobes overlapping and leaf margins recurving at the hydathodes,. whereas Diplaspis hydrocotyle only has bisexual flowers and has no overlapping...
and they have been found to invade the plant host through wounds or hydathodes. Xanthomonas campestris pv. campestris also has some limited ability to...
. Veins free, pinnately branching, veinlet not reaching margin, with hydathode at apex. Sori orbicular, marginal, terminal on each veinlet, separate...
with a pointed tip, and up to about 10 (range: 4-18) blunt teeth, with a hydathode at the tip, along each side. Plants can be male, female or hermaphrodite...
secreted by the plant's leaf margins, where secreting pores consisting of hydathode tissue are located. Similar calcium carbonate excretion is exhibited by...
hairs projecting horizontally. The leaves have green or purple tips (hydathodes) on each tooth. The flowering period is between May and October in northern...
sometimes entire (rounded) but more often angled or weakly lobed, with hydathodes at the tips. There are two types of roots: dense clusters of thick, pale-coloured...
ovate, 4-7 mm long by 2-3 mm wide, with a pale green or sometimes purple hydathode at the pointed tip and stomata on both sides. The petioles are flattened...
palmatinerved, bifacial, rarely isofacial; in Angelisia and Anamirta, with hydathodes derived from trichomes. Domatia present in five genera as pits or hair...
bacteria. It normally enters its host plants through stomatal openings or hydathodes. Wounds to stems have also been noted as a means of entry. Once inside...
arranged in opposite pairs, between 2–20 mm long and 1.5–6 mm wide, with a hydathode at the tip. On some plants, particularly those floating in water, the...
Global Information