Tsuga is a genus of conifers in the subfamily Abietoideae of Pinaceae, the pine family. The English-language common name "hemlock" arose from a perceived similarity in the smell of its crushed foliage to that of the unrelated plant poison hemlock. Unlike the latter, Tsuga species are not poisonous.
Tsuga canadensis, also known as eastern hemlock, eastern hemlock-spruce, or Canadian hemlock, and in the French-speaking regions of Canada as pruche du Canada, is a coniferous tree native to eastern North America. It is the state tree of Pennsylvania. Eastern hemlocks are widespread throughout much of the Great Lakes region, the Appalachian Mountains, the Northeastern United States, and Maritime Canada. They have been introduced in the United Kingdom and mainland Europe, where they are used as ornamental trees.
Tsuga heterophylla, the western hemlock or western hemlock-spruce, is a species of hemlock native to the west coast of North America, with its northwestern limit on the Kenai Peninsula, Alaska, and its southeastern limit in northern Sonoma County, California. The Latin species name means 'variable leaves'.
Tsuga mertensiana, known as mountain hemlock, is a species of hemlock native to the west coast of North America, found between Southcentral Alaska and south-central California.
Tsuga caroliniana, the Carolina hemlock, is a species of hemlock endemic to the United States. As of 2023, it is under review for listing under the Endangered Species Act of 1973.
Adelges tsugae, the hemlock woolly adelgid or HWA, is an insect of the order Hemiptera native to East Asia. It feeds by sucking sap from hemlock and spruce trees. In its native range, HWA is not a serious pest because populations are managed by natural predators and parasitoids and by host resistance. In eastern North America it is a destructive pest that threatens the eastern hemlock and the Carolina hemlock. HWA is also found in western North America, where it has likely been present for thousands of years. In western North America, it primarily attacks western hemlock Tsuga heterophylla and has only caused minor damage due to natural predators and host resistance. Accidentally introduced to North America from Japan, HWA was first found in the eastern United States near Richmond, Virginia, in 1951. The pest is now found from northern Georgia to coastal Maine and southwestern Nova Scotia as well as areas of western Michigan near the eastern Lake Michigan shoreline. As of 2015, HWA has affected 90% of the geographic range of eastern hemlock in North America.
Tsuga dumosa, commonly called the Himalayan hemlock or in Chinese, Yunnan tieshan, is a species of conifer native to the eastern Himalayas. It occurs in parts of Nepal, India, Bhutan, Myanmar, Vietnam and Tibet. Within its native range the tree is used for construction as well as for furniture. In Europe and North America, it is occasionally encountered as an ornamental species and was first brought to the United Kingdom in 1838.
Tsuga chinensis, commonly referred to as the Taiwan or Chinese hemlock, is a coniferous tree species native to China, Taiwan, and Vietnam. The tree is quite variable and has many recognised varieties, though some are also maintained to be separate species by certain authorities. The tree was recently discovered in the mountains of northern Vietnam, making that the southernmost extension of its range.
Acleris sparsana is a moth of the family Tortricidae found in Europe and Iran. It was first described in 1775 by the Austrian lepidopterists Michael Denis and Ignaz Schiffermüller.
Acleris variegana, the garden rose tortricid moth or fruit tortricid, is a moth of the family Tortricidae. It has a Palearctic distribution. The moth flies from July to September mainly at night and is attracted to bright lights. The larvae feed on various trees and shrubs including rose and apple.
Acleris semipurpurana is a species in the moth family Tortricidae, and one of several species of moth commonly known as oak leaftier or oak leaf tier. The larvae feed on the leaves of oak trees in the Eastern United States and southeastern Canada which can be a major cause of defoliation. The loss of leaves can kill or damage the affected trees, which are chiefly in the Lobatae or red oak section of Quercus, or oaks.
Acleris emargana, the notched-winged tortricid, is a moth of the family Tortricidae. The species was first described by Johan Christian Fabricius in 1775.
Acleris is a genus of moths belonging to the subfamily Tortricinae of the family Tortricidae. As of 2007, about 241 species were known.
Acleris literana, the sprinkled rough-wing, is a moth of the family Tortricidae. The species was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae. It is found in most of Europe and in the Near East.
Acleris maccana, the marbled dog's-tooth tortrix, is a moth of the family Tortricidae. The species was first described by Georg Friedrich Treitschke in 1835. It is found from Europe, east across the boreal regions to Siberia.
Pleurocybella porrigens is a species of fungus in the family Phyllotopsidaceae. The species is widespread in temperate forests of the Northern Hemisphere. P. porrigens, known as the angel wing, is a white-rot wood-decay fungus on conifer wood, particularly hemlock. The flesh is thin and fragile compared to the oyster mushrooms.
Acleris ferrugana is a species of moth of the family Tortricidae. It is found in China, most of Europe and has also been recorded from North America.
Acleris schalleriana, the viburnum button or Schaller's acleris moth, is a moth of the family Tortricidae. It was described by Carl Linnaeus in 1761. It is found in most of Europe. It is also found in North America. Acleris viburnana is a possible synonym that refers to the North American populations.
Acleris quercinana is a species of moth of the family Tortricidae. It was described by Zeller in 1849. It is found in most of Europe, Asia Minor and Iran.
The mid-Holocene hemlock decline was an abrupt decrease in Eastern Hemlock populations noticeable in fossil pollen records across the tree's range. It has been estimated to have occurred approximately 5,500 calibrated radiocarbon years before 1950 AD. The decline has been linked to insect activity and to climate factors. Post-decline pollen records indicate changes in other tree species' populations after the event and an eventual recovery of hemlock populations over a period of about 1000-2000 years at some sites.
