Marcescence
Encyclopedia
Marcescence is the retention of dead plant organs that normally are shed. It is most obvious in deciduous trees that retain leaves through the winter. Several trees normally have marcescent leaves such as oak
(Quercus), beech
(Fagus) and hornbeam
(Carpinus). Marcescent leaves of pin oak
(Quercus palustris) complete development of their abscission
layer in the spring. The base of the petiole remains alive over the winter. Many other trees may have marcescent leaves in seasons where an early freeze kills the leaves before the abscission
layer develops or completes development. Diseases or pests can also kill leaves before they can develop an abscission layer.
The term "marcescent" is also used in mycology
to describe a mushroom which (unlike most species, described as "putrescent") can dry out, but later revive and continue to disperse spores. Genus Marasmius
is well-known for this feature, which was considered taxonomically important by Elias Magnus Fries
in his 1838 classification of the fungi.
s, such as deer
and moose
, which normally eat the twigs and their nutritious buds. Dead, dry leaves make the twigs less nutritious and less palatable.
Marcescent leaves may protect some species from water stress or temperature stress. For example, in tropical alpine environments a wide variety of plants in different plant families and different parts of the world have evolved a growth form known as the caulescent rosette, characterized by evergreen rosettes growing above marcescent leaves. Examples of plants for which the marcescent leaves have been confirmed to improve survival, help water balance, or protect the plant from cold injury are Espeletia
schultzii and Espeletia timotensis, both from the Andes
.
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
(Quercus), beech
Beech
Beech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.-Habit:...
(Fagus) and hornbeam
Hornbeam
Hornbeams are relatively small hardwood trees in the genus Carpinus . Though some botanists grouped them with the hazels and hop-hornbeams in a segregate family, Corylaceae, modern botanists place the hornbeams in the birch subfamily Coryloideae...
(Carpinus). Marcescent leaves of pin oak
Pin oak
Quercus palustris, the Pin oak or Swamp Spanish oak, is an oak in the red oak section Quercus sect. Lobatae.-Distribution:...
(Quercus palustris) complete development of their abscission
Abscission
Abscission is a term used in several areas of biology. In plant sciences it most commonly refers to the process by which a plant drops one or more of its parts, such as a leaf, fruit, flower or seed...
layer in the spring. The base of the petiole remains alive over the winter. Many other trees may have marcescent leaves in seasons where an early freeze kills the leaves before the abscission
Abscission
Abscission is a term used in several areas of biology. In plant sciences it most commonly refers to the process by which a plant drops one or more of its parts, such as a leaf, fruit, flower or seed...
layer develops or completes development. Diseases or pests can also kill leaves before they can develop an abscission layer.
Mycology
Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, medicinals , food and entheogens, as well as their dangers, such as poisoning or...
to describe a mushroom which (unlike most species, described as "putrescent") can dry out, but later revive and continue to disperse spores. Genus Marasmius
Marasmius
Marasmius is a genus of mushrooms, in the family Marasmiaceae. It contains about 500 species of agarics, of which a few, such as Marasmius oreades, are edible. However, most members of this genus are small, unimpressive brown mushrooms...
is well-known for this feature, which was considered taxonomically important by Elias Magnus Fries
Elias Magnus Fries
-External links:*, Authors of fungal names, Mushroom, the Journal of Wild Mushrooming.*...
in his 1838 classification of the fungi.
Benefits
One possible advantage of marcescent leaves is that they may deter feeding of large herbivoreHerbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s, such as deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
and moose
Moose
The moose or Eurasian elk is the largest extant species in the deer family. Moose are distinguished by the palmate antlers of the males; other members of the family have antlers with a dendritic configuration...
, which normally eat the twigs and their nutritious buds. Dead, dry leaves make the twigs less nutritious and less palatable.
Marcescent leaves may protect some species from water stress or temperature stress. For example, in tropical alpine environments a wide variety of plants in different plant families and different parts of the world have evolved a growth form known as the caulescent rosette, characterized by evergreen rosettes growing above marcescent leaves. Examples of plants for which the marcescent leaves have been confirmed to improve survival, help water balance, or protect the plant from cold injury are Espeletia
Espeletia
Espeletia, commonly known as Frailejón or Fraylejón is a genus of perennial subshrubs, in the family Asteraceae. The genus, which is endemic mainly to Colombia, Venezuela and Ecuador, was first formally described by botanist Alexander Von Humboldt in 1801...
schultzii and Espeletia timotensis, both from the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
.