''Alnus maritima'', the seaside alder or brook alder, is a species of shrub or small tree in the family

Betulaceae Betulaceae, the birch family, includes six genera of deciduous nut-bearing trees and shrubs, including the birches, alders, hazels, hornbeams, hazel-hornbeam, and hop-hornbeams numbering a total of 167 species. They are mostly natives of the t ...

. ''Alnus maritima'' is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the United States, and is found naturally in three disjunct populations in

Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...

, and in

Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...

and

Delaware Delaware ( ) is a state in the Mid-Atlantic region of the United States, bordering Maryland to its south and west; Pennsylvania to its north; and New Jersey and the Atlantic Ocean to its east. The state takes its name from the adjacent Del ...

on the

Delmarva Peninsula The Delmarva Peninsula, or simply Delmarva, is a large peninsula and proposed state on the East Coast of the United States, occupied by the vast majority of the state of Delaware and parts of the Eastern Shore regions of Maryland and Virginia ...

. ''Alnus maritima'' is the only autumn-blooming member of the genus ''

Alnus Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...

'' native to North America. All other North American alders bloom in the spring. The autumn-blooming

phenology Phenology is the study of periodic events in biological life cycles and how these are influenced by seasonality, seasonal and interannual variations in climate, as well as environmental factor, habitat factors (such as elevation). Examples includ ...

is a characteristic that ''Alnus maritima'' shares with two old-world ''Alnus'' species, ''

Alnus nitida ''Alnus nitida'', the west Himalayan alder, is a species in the genus ''Alnus'', native to Pakistan, the western Himalayas, and Nepal. It is a tree reaching 20 to 25m, preferring to live along the banks of rivers. It is used locally for timber an ...

'' and ''

Alnus nepalensis ''Alnus nepalensis'' is a large alder tree found in the subtropical highlands of the Himalayas. The tree is called Utis in Nepali and Nepalese alder in English. It is used in land reclamation, as firewood and for making charcoal. Description ...

'', which are endemic to

southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

. This profound similarity in their timing of anthesis has led to their classification as the only three members in the subgenus ''Clethropsis''.

Taxonomy

In 2002, the three populations were recognized as

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

and given the names ''Alnus maritima'' subsp. ''oklahomensis'', ''Alnus maritima'' subsp. ''georgiensis'', and ''Alnus maritima'' subsp. ''maritima'', respectively. While some believe that subspecies ''maritima'' is the oldest of the three subspecies and that the other two disjunct populations resulted from some form of long distance dispersal, evidence from morphometric and

phylogeographic Phylogeography is the study of the historical processes that may be responsible for the past to present geographic distributions of genealogical lineages. This is accomplished by considering the geographic distribution of individuals in light of ge ...

studies indicates that the Oklahoma population (subsp. ''oklahomensis'') is in fact the most ancestral and that the species probably had a wide, continuous distribution across the United States in the past.

References

External links

* * {{Taxonbar, from=Q2589489 maritima Endemic flora of the United States Taxonomy articles created by Polbot