One of the most serious problems that plants face is ice crystal formation in the cells, which results in tissue death. Plants have two ways to resist freezing: avoid it or tolerate it. If a plant has taken the avoidance route, it has several different ways to evade freezing. It can build up insulation, have its stem close to the ground, use the insulation from snow cover, and supercool. When supercooling, water is able to remain in its liquid state down to −38 °C or −36 °F (compared to its usual 0 °C or 32 °F freezing point). After water reaches −38 °C (−36 °F), it spontaneously freezes and plant tissue is destroyed. This is called the nucleation point. The nucleation point can be lowered if dissolved solutes are present.
If a plant has taken the tolerance route, it has several different ways to tolerate freezing. Some plants allow freezing by allowing extracellular, but not intracellular freezing. Plants let water freeze in extracellular spaces, which creates a high vapor deficit that pulls water vapor out of the cell. This process dehydrates the cell and allows it to survive temperatures well below −38 °C (−36 °F).
Another problem associated with extreme cold is cavitation. Ring-porous wood is susceptible to cavitation because the large pores that are used for water transport easily freeze. Cavitation is much less of problem in trees with ring-diffuse wood. In ring-diffuse wood, there is a reduced risk of cavitation, as transport pores are smaller. The trade-off is that these species are not able to transport water as efficiently.
... common form of urticating bristles in plants are typified by nettles, which possess sharp-pointed hollow bristles seated on a gland which secretes an acrid fluid ... Various plants unrelated to nettles possess similar defensive bristles, and the common names often reflect this (e.g ...
... Ebenaceae is a family of flowering plants, belonging to order Ericales, which includes ebony and persimmon among approximately 768 species of trees and shrubs ... The species are mostly evergreen plants native to the tropics and subtropics, with a few deciduous species native to temperate regions ... Ebenaceae are woody plants that frequently grow in poor or acids soils establishing a mycorrhizal symbiotic relationship with particular fungus species providing mainly ...
... the meaning of the Weeds Act, and many such plant species have conservation and environmental value. 1959 act, under section 14 of the Wildlife and Countryside Act 1981, it can be an offence to plant or grow certain specified plants in the wild (see Schedule 9 to the ... Problems involving these plants can be referred to the local authority for the area where those weeds are growing as some local authorities have bye-laws ...
... The few remaining plants still in operation run at reduced capacity and employ fewer workers ... Despite the loss of the textile plants, Belmont continues to grow ... Gastonia-based Parkdale Mills currently operates two plants (Plants No ...
Famous quotes containing the word plants:
“Luxurious Man, to bring his Vice in use,
Did after him the World seduce:
And from the fields the Flowrs and Plants allure,”
—Andrew Marvell (16211678)
“Brute force crushes many plants. Yet the plants rise again. The Pyramids will not last a moment compared with the daisy. And before Buddha or Jesus spoke the nightingale sang, and long after the words of Jesus and Buddha are gone into oblivion the nightingale still will sing. Because it is neither preaching nor commanding nor urging. It is just singing. And in the beginning was not a Word, but a chirrup.”
—D.H. (David Herbert)
“All plants move, but they dont usually pull themselves out of the ground and chase you.”
—Philip Yordan (b. 1913)