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Topic: Hydathodes

	Secretory Structures (Site not responding. Last check: 2007-10-17)
		Hydathodes are external secretory structures exuding water which appears as droplets on the surface of the organ in a process called guttation.
		Two types of hydathodes are recognized: 1 active: usually in the form of glandular trichomes in which water is actively exuded by secretory cells which are not connected to water-conducting tracheary elements, and 2 passive: usually located at leaf margins or tips of leaves.
		In passive hydathodes, water is released from the tracheary elements and then passes through intercellular spaces of the epithem, or modified mesophyll cells.
	www.cls.zju.edu.cn /sub/fulab/plantanatomy/secret (653 words)

	hydathode - Hutchinson encyclopedia article about hydathode (Site not responding. Last check: 2007-10-17)
		Hydathodes are found on many different plants and are usually situated around the leaf margin at vein endings.
		Each pore is surrounded by two crescent-shaped cells and resembles an open stoma, but the size of the opening cannot be varied as in a stoma.
		The process of water secretion through hydathodes is known as guttation.
	encyclopedia.farlex.com /hydathode (143 words)

	Universität Münster: Forschungsbericht 1999-2000 - Inhaltsverzeichnis Institut für Ökologie der ...
		Hydathodes are leaf structures which normally serve the extrusion of liquid water, a process termed guttation.
		In several cases wetting only the older leaves on the lower portion of the shoot not only resulted in increased thickness of these leaves, but also effected an increase in leaf thickness and stimulation of CO uptake rates in the distal, younger portion of the leaf that was not wetted.
		Generally, foliar hydathodes were implicated in the absorption of surface water in most of the species investigated in a way that the ecophysiology of these desert succulents was positively affected.
	www.uni-muenster.de /Rektorat/Forschungsberichte-1999-2000/fo13bd02.htm (266 words)

	Saxifragaceae of the Canadian Arctic Archipelago - Saxifraga oppositifolia L.
		Conspicuous hydathodes present (seen as pores on the thickened, often flat, apex of the leaf; often with white calcium carbonate deposits; illustrated in the image library).
		They are entirely absent from the tip of the apex where the hydathode is. Immediately behind the apex they occur in a broad band across the leaf and are partially continued along the under-side of the leaf margin.
		Hydathodes are small openings on the leaf blades which exude water.
	www.mun.ca /biology/delta/arcticf/sax/www/sxsxop.htm (1649 words)

	Crassula subgenus explained :: Succulent Plant Site (Site not responding. Last check: 2007-10-17)
		Hydathodes are marginal and are seldom found on both sides of the leaves.
		The glabrous leaves are flat with hydathodes appearing in dense rows on the margins.
		The leaves are sessile and have hydathodes scattered over one or both of the surfaces, if the hydathodes do occur on the margins they appear in dense rows.
	www.succulents.co.za /crassula/crass_subgen.shtml (1676 words)

	Black Rot of Crucifers Fact Sheet
		The infected tissue is wilted and pale green initially (fig.
		Bacteria enter leaves through hydathodes when water exuded through these pores at the leaf margin during the night is drawn back into the plant in the morning.
		Bacterial movement into plants through hydathodes is restricted in resistant varieties; consequently, there are fewer infection sites and/ or the affected area is much smaller in resistant varieties than in susceptible varieties.
	vegetablemdonline.ppath.cornell.edu /factsheets/Crucifers_BR.htm (1265 words)

	MSN Encarta - Leaf
		These pores, called hydathodes, permit guttation, the process by which a plant loses liquid water.
		Unlike the stomata, hydathodes remain open all the time.
		Guttation takes place only when water is being rapidly absorbed by the roots, such as after a heavy rainfall, and when transpiration slows down, as on cool, humid nights.
	ca.encarta.msn.com /encyclopedia_761558729_2/Leaf.html (711 words)

	[No title] (Site not responding. Last check: 2007-10-17)
		We find so far the follow characters are stable: glabrous or hairy on leaf blade surface and the hair form (jointed hair or seta), leaf margin (entire or serrate), the shape and locality of the hydathodes (far from the tooth at leaf margin, extending into the tooth, or even fusing with the cartilaginos tooth margin).
		Hydathodes extending into teeth and closing up to or fusing with tooth margin.
		Hydathodes closing up to tooth margin but not fusing with it.
	flora.huh.harvard.edu /china/mss/volume02/Pteridophytes-part_original.htm (13452 words)

	BBC - 16+ SOS Teacher - Biology cells Plants
		Some plants have water stomata (also called hydathodes) or ordinary stomata at their leaf margins that secrete the water as droplets.
		The hydathodes, that can often be found at the end of vascular bundles are derivatives of stomata.
		Characteristic hydathodes occur especially at the leaf margins of Garden Nasturtium (Tropaeolum majus, and at the leaves tips of many grasses.
	www.bbc.co.uk /schools/16/sosteacher/biology/32642.shtml (366 words)

	Guttation - Open Encyclopedia (Site not responding. Last check: 2007-10-17)
		On some nights when atmospheric conditions are not conducive to transpiration (humid and windless), and when there is a high soil moisture, guttation occurs to maintain the flow of water and nutrients through the plant.
		In that event, the water will exude through special leaf tip cells, hydathodes in the leaves, forming drops of water.
		Root pressure provides the impetus for this flow, rather than transpiration pull.
	www.open-encyclopedia.com /Guttation (130 words)

	Unit 7
		Hydathodes are sites of water escape when root pressure is high enough and transpiration rates low enough for guttation.
		The hydathode consists of a flaired bundle of tracheary elements which connect to small parenchyma cells called "epithem".
		Hydathodes in this species are only of the adaxial surface.
	trc.ucdavis.edu /plb/PLB105/html/Un7.html (1700 words)

	Abstract (Site not responding. Last check: 2007-10-17)
		Specialized structures in the epidermis of the leaves, called hydathodes may be responsible for foliar water uptake in the plants thus helping them to survive in arid conditions.
		Researchers have theorized that the remarkable ability of CAM plants to survive on such little precipitation is due in part to the presence of hydathodes.
		Researchers have hypothesized that the water is absorbed by the hydathodes.
	departments.oxy.edu /urc/projects/abstracts/2000/00biologyCh.htm (254 words)

	IPM : Reports on Plant Diseases : Black Rot of Cabbage and Other Crucifers
		The result is initially a small, wilted, V-shaped infected area that extends inward from the leaf edge toward the midrib (Figures 1-2).
		The pathogen is spread from plant to plant by splashing rain, or in films of water moved by people, equipment, insects, and other animals.
		The bacteria enter the plant through hydathodes along the leaf margins, through insect injuries, and in very susceptible crops, such as cauliflower, directly through the stomates.
	www.ipm.uiuc.edu /diseases/series900/rpd924/index.html (1358 words)

	Plant Physiology Online: Free Auxin Production and Vascular Differentiation in Arabidopsis Leaves
		Hydathodes, the water secreting glands which develop in the tip and later in the lobes, are the primary sites of free IAA production in a leaf blade, while trichomes and mesophyll cells are the secondary sites.
		During leaf development there is a gradual shift in the site of free IAA production, occurring first in the tip of a primordium, then progressing basipetally along the leaf margins, and finally appearing also in the lamina.
		From the differentiating hydathodes which are the major sites of free auxin production (see Figures 2C and 2D) the hormone moves basipetally and induces the midvein and the secondary bundles (see Figures 1B-D; Taiz and Zeiger, 2002, Fig.
	www.plantphys.net /article.php?ch=19&id=283 (1453 words)

	Cryptogramma in Flora of North America @ efloras.org
		Stems 4–20 mm diam., decumbent to erect, many branched from base; leaves strongly tufted, herbaceous to somewhat leathery, present throughout growing season; petioles dark brown in proximal 1/8 or less; mostly of noncalcareous habitats.
		Blades herbaceous, thin, translucent when dried, shed in autumn, not persistent; hydathodes on dried leaves superficial; hairs absent from adaxial leaf surface.
		Blades somewhat leathery, opaque when dried, green and persistent over winter; hydathodes on dried leaves sunken below surface; hairs small, appressed, cylindric, present in grooves of petiole, costae, and costules of adaxial leaf surface.
	www.efloras.org /florataxon.aspx?flora_id=1&taxon_id=108536 (332 words)

	Plant Pathology Lesson 2
		Stomata, hydathodes (water pores), lenticels and rifts in the root cortex as a result emergence of secondary roots are examples of natural openings.
		This bacterium enters through hydathodes at the leaf margin and progresses inter and intracellular and eventually reaches the vascular system becoming systemic.
		Infection: This is the next step in the disease cycle and is the process where the pathogen has not only penetrated, but has established a food relationship with the host and is able to extract nutrients from the host.
	www.selu.edu /Academics/Faculty/wbond/online401/lesson2.html (1311 words)

	[No title] (Site not responding. Last check: 2007-10-17)
		It is readily separated from W. plummerae by the characteristics given in the key, and from North American members of the mexicana group (W. phillipsii and W. neomexicana) by having indusial segments that are broad and nonfilamentous at the base.
		Woodsia cochisensis is less glandular than typical W. mexicana from northeastern Mexico and is further distinguished from that species by the thickened, lustrous pinnule margins and well-developed hydathodes.
		Isozyme and chromosome studies suggest that W. cochisensis is an allotetraploid that may have originated through hybridization between W. phillipsii and an undescribed Mexican diploid (M. Windham 1993).
	www.canis.uiuc.edu /~pheidorn/kmreiss/textproc/numericdatatest/datafiles/s_Woodsia_cochisensis.xml (316 words)

	Flora of the Canadian Arctic Archipelago - Saxifraga paniculata P. Mill.
		Plants perennial herbs; 7–20 cm high (to 25 cm high in Greenland specimens); with a basal rosette of leaves that are often have conspicous white deposits at the hydathodes; vegetatively proliferating by bulbils or fragmentation (lateral shoots, often closely associated with the parent shoot).
		Blade margins glandular-dotted (hydathodes, not glands), or serrulate, or crenate; with 7–10 glands per cm (hydathodes); glabrous.
		The epidermis of the hydathode has 1–2 water pores and some of the cells are elongated as papillae.
	www.mun.ca /biology/delta/arcticf/_ca/www/sxsxpa.htm (915 words)

	Thieme-connect - Abstract (Site not responding. Last check: 2007-10-17)
		Epidermal hydathodes were found on leaves of 46 of 48 species of
		The presence of hydathodes on leaf epidermi correlated, in most cases, with increases in leaf thickness and enhanced rates of nocturnal, and sometimes diurnal, CO uptake following wetting of the leaves during the night.
		Overall, foliar hydathodes were implicated in the absorption of surface water in many species of
	www.thieme-connect.com /ejournals/abstract/plantbiology/doi/10.1055/s-2000-9163 (303 words)

	American Journal of Botany, 55, 4, April, 1968 (Site not responding. Last check: 2007-10-17)
		The pentamerous, zygomorphic corolla is bilabiate, consisting of a three-lobed adaxial lip and a two-lobed abaxial lip connected by a short tubular region.
		The constituent petal lobes are also uni-traced and have a reticulate venation, resembling that of the sepal and bract, but lack storage tracheids and hydathodes.
		Sepals arise in an adaxial to abaxial succession and are initiated in the outer corpus layer of the floral apex.
	www.botany.org /ajb/00029122_di001668.php (2786 words)

	Elaphoglossum Subgroups
		The clade is characterized by subulate scales and/or hydathodes.
		Within the clade, there is a monophyletic group (boryanum - eximium) characterized by hydathodes, and another monophyletic group (species 1 - auripilum on the evolutionary tree) characterized by short-petiolate or sessile leaves.
		It differs from the rest of the genus by the combination of hydathodes, phyllopodia, and reddish young leaves.
	www.nybg.org /bsci/res/moran/elaphoglossum_subgroups.html (239 words)

	[No title] (Site not responding. Last check: 2007-10-17)
		Guttation is due to pressure in the xylem that forces water out pores in leaves called hydathodes.
		The hydathodes are opening at the end of veins to allow water under pressure to escape.
		Water drips from the leaves through the hydathodes to releave this pressure.
	homepage.smc.edu /hodson_kent/Chemistry/Circulation/guttation.htm (189 words)

	Overexpression of GLUTAMINE DUMPER1 Leads to Hypersecretion of Glutamine from Hydathodes of Arabidopsis Leaves -- Pilot ...
		The structure of the hydathodes suggests an involvement not
		Bürkle, L., Cedzich, A., Dölpke, C., Stransky, H., Okumoto, S., Gillissen, B., Kühn, K., and Frommer, W.B. Transport of cytokinins mediated by purine transporters of the PUP family expressed in phloem, hydathodes, and pollen of Arabidopsis.
		Takeda, F., and Glenn, M.D. Hydathode anatomy and the relationship between guttation and plant water status in strawberry (Fragaria x ananassa Duch.).
	www.plantcell.org /cgi/content/full/16/7/1827 (7797 words)

	Notes, Observations, and Ideas Relating to Giant Equisetum
		In Equisetum, these are structures that are associated with veins on the leaf and/or sheath (Johnson, 1936) and serve as exit routes for xylem water when there is positive hydrostatic pressure (called root pressure) in the xylem (Nobel, 1991).
		The exit of this xylem water, termed guttation, results in the formation of small droplets in the vicinity of the hydathodes.
		Johnson (1936) studied the anatomy of hydathodes in many Equisetum species and noted that the hydathodes of E.
	www.fiu.edu /~chusb001/GiantEquisetum/NotesObservationsIdeas.html (3412 words)

	Crying Plants, Why do plants tear?
		When leaves lose water as a liquid phase through special cells called hydathodes it is referred to as guttation.
		These guttation "tears" appear at the leaf tips or margins and contain various salts, sugars and other organic substances.
		The use of some leaf cleaners and leaf shines can also plug up the hydathodes and cause browning tips.
	www.plant-care.com /crying-plants.html (469 words)

	Overexpression of GLUTAMINE DUMPER1 Leads to Hypersecretion of Glutamine from Hydathodes of Arabidopsis Leaves -- Pilot ...
		Overexpression of GLUTAMINE DUMPER1 Leads to Hypersecretion of Glutamine from Hydathodes of Arabidopsis Leaves -- Pilot et al.
		was identified that accumulates salt crystals at the hydathodes.
		GDU1 is expressed in the vascular tissues and in hydathodes.
	www.plantcell.org /cgi/content/abstract/16/7/1827 (313 words)

	Organosilicone Surfactants - Spraytec
		Now, this is not the kind of approach for crops that we want to grow, nurture, and develop into quality, profitable products.
		Organosilicones are so efficient at spreading materials, that they have been known to enter plant stomata and hydathodes* - organs not normally penetrated by other surfactants.
		Hydathodes are the tiny openings along the leaf margins that allow excess water to escape during the night.
	www.spraytec.com /articles/AprilMay98/Organosilocones.asp (326 words)

	Leaf Wetness and Turfgrass Disease Colorado State University Cooperative Extension Tri River Area
		This is a fluid rich in carbohydrates and amino acids exuded from the tip of the grass blade.
		Special structures called hydathodes exude this solution when water pressure builds up in the plant as occurs in the cool night hours.
		This nutrient rich solution serves as a food source for fungus to grow and infect the plant.
	www.colostate.edu /Depts/CoopExt/TRA/PLANTS/leafwet.html (1694 words)

	My Zamioculcas Plant
		In March/April 2002, when the plant was unfolding a new leaf, guttation was observed from leaflet margins at two occasions in the early morning hours.
		Guttation is the exudation of liquid water (as a result of osmotic root pressure) that is released by special cells (hydathodes).
		This enables the basipetal transport of dissolved nutrients under conditions of high (even of condensing) air humidity, when evaporation is low.
	members.chello.at /norbert.anderwald/Zamioculcas/my_plant_e.htm (556 words)

	Plant surface beauties
		A leaflet of fern has on its upper surface on both its edges rows of hydathodes.
		Water is secreted out of the tissues (guttation), and as water evaporates calcium salts are left behind in the form of white chalk like crust.
		Hydathodes are therfore also known as chalk glands or water stomata.
	www.suite101.com /article.cfm/9661/89903 (597 words)

	Tropical Bonsai Forums - What's up with my Ficus?
		what you are witnessing is water exuding from the hydathodes on the plants leaves.
		Drops of water are then forced out of the leaf through special stomata or hydathodes.
		Yabbyman, thank you for clearing this up for me, just to let you know it only lasted for 1 day and after 3 days the tops and bottoms of the leaves seem to be completely back to normal(the bottoms got very dark in color right around the hydathodes).
	www.tropicalbonsai.com /forums/showthread.php?t=274 (382 words)

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