Populus is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar, aspen, and cottonwood.
Populus section Aigeiros is a section of three species in the genus Populus, the poplars. Like some other species in the genus Populus, they are commonly known as cottonwoods. The species are native to North America, Europe, and western Asia. In the past, as many as six species were recognized, but recent trends have been to accept just three species, treating the others as subspecies of P. deltoides.
Galls or cecidia are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or warts in animals. They can be caused by various parasites, from viruses, fungi and bacteria, to other plants, insects and mites. Plant galls are often highly organized structures so that the cause of the gall can often be determined without the actual agent being identified. This applies particularly to some insect and mite plant galls. The study of plant galls is known as cecidology.
Salix caprea, known as goat willow, pussy willow or great sallow, is a common species of willow native to Europe and western and central Asia.
The Aphididae are a very large insect family in the aphid superfamily (Aphidoidea), of the order Hemiptera. These insects suck the sap from plant leaves. Several thousand species are placed in this family, many of which are considered plant/crop pests. They are the family of insects containing most plant virus vectors with the green peach aphid being one of the most prevalent and indiscriminate carriers.
Gall wasps, also incorrectly called gallflies, are hymenopterans of the family Cynipidae in the wasp superfamily Cynipoidea. Their common name comes from the galls they induce on plants for larval development. About 1,300 species of this generally very small creature are known worldwide, with about 360 species of 36 different genera in Europe and some 800 species in North America.
Woolly aphids are sap-sucking insects that produce a filamentous waxy white covering which resembles cotton or wool. The adults are winged and move to new locations where they lay egg masses. The nymphs often form large cottony masses on twigs, for protection from predators.
Abscission is the shedding of various parts of an organism, such as a plant dropping a leaf, fruit, flower, or seed. In zoology, abscission is the intentional shedding of a body part, such as the shedding of a claw, husk, or the autotomy of a tail to evade a predator. In mycology, it is the liberation of a fungal spore. In cell biology, abscission refers to the separation of two daughter cells at the completion of cytokinesis.
Populus deltoides, the eastern cottonwood or necklace poplar, is a cottonwood poplar native to North America, growing throughout the eastern, central, and southwestern United States as well as the southern Canadian prairies, the southernmost part of eastern Canada, and northeastern Mexico.
The witch-hazel cone gall aphid is a minuscule insect, a member of the aphid superfamily, whose presence on a witch-hazel plant is easily recognizable by a conical gall structure. The gall is green at first, then turns bright red. This gall, rich in nutrients, provides both food and shelter for the female aphid.
Populus trichocarpa, the black cottonwood, western balsam-poplar or California poplar, is a deciduous broadleaf tree species native to western North America. It is used for timber, and is notable as a model organism in plant biology.
Populus angustifolia, commonly known as the narrowleaf cottonwood, is a species of tree in the willow family (Salicaceae). It is native to western North America, where it is a characteristic species of the Rocky Mountains and the surrounding plains. It ranges north to the provinces of Alberta and Saskatchewan in Canada and south to the states of Chihuahua, Coahuila, and Sonora in Mexico. Its natural habitat is by streams and creeks between 3,900 to 7,900 feet elevation.
Pistacia atlantica is a species of pistachio tree known by the English common name Mt. Atlas mastic tree, Atlas pistachio, Atlantic pistacio, Atlantic terebinth, Cyprus turpentine tree, and Persian turpentine tree.
Populus heterophylla, also known as downy poplar, swamp poplar and swamp cottonwood, is a large deciduous poplar belonging to the Populus genus of the family Salicaceae. This species can grow on sites that have too much water for other native poplars. On the IUCN Red List this species is listed as "least concern".
Ectoedemia turbidella is a moth of the family Nepticulidae and is found in most of Europe. The larva mine the leaves of poplar trees and was first described by the German entomologist Philipp Christoph Zeller in 1848.
Pemphigus spyrothecae, or the poplar spiral gall aphid, is a social insect which exhibits apparent altruistic behaviors. The aphids form galls and act as colony defenders, at times sacrificing their own lives to do so. It has been shown that colony defense is more likely in habitats that are difficult to obtain and can hold a large number of individuals. These gall locations are crucial because plants have a short window in which a gall can be produced. Thus, it is important for there to be a defense system that enables the aphids to retain their galls. The need for defense arises when the gall is opened up to allow winged aphid migrants to leave and to release any waste. The process of repairing the holes can take up to 10 days; during this time, the gall is susceptible to intruding predators.
Pemphigus betae, also known as the sugarbeet root aphid, is a species of gall-forming aphid that forms galls specifically on the commonly found narrowleaf cottonwood, Populus angustifolia. Sugarbeet root aphids have been found in North America and Europe. They infect sugarbeets, but also other plants like tablebeets and Swiss chard. Their size has been likened to that of a pinhead, and are pale white-yellow in color. Sugarbeet root aphids have soft bodies that are bulbous in shape, with mandibular parts that can pierce and suck and paired abdominal tubes that point backwards, and come in both winged and wingless forms. They are known for their consequential effects on agriculture due to infestation of plants, and efforts to control the pests have proved to be difficult.
Pemphigus obesinymphae is a species of gall-forming aphid. It creates galls on the leaves of Populus fremontii. The species is the only North American aphid known to have soldiers, first instar nymphs that defend the colony.
Amphibolips quercuspomiformis, also known as the apple gall wasp or live oak apple gall wasp, is a species of gall wasp. It induces galls in coast live oak and interior live oak trees. Like many gall wasps, it has two alternating generations: a parthenogenic generation, and a bisexual generation. The galls formed by the all-female parthenogenic generation are spherical, up to 40 mm in diameter, and covered with short spines. They form on stems and are green or red when new, then turn brown. The galls formed by the bisexual generation are small, shaped like toadstools, and occur on leaves.
