Alnus maritima
Encyclopedia
Alnus maritima is a species of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

 in the Betulaceae
Betulaceae
Betulaceae, or the Birch Family, includes six genera of deciduous nut-bearing trees and shrubs, including the birches, alders, hazels, hornbeams and hop-hornbeams, numbering about 130 species...

 family. Alnus maritima is endemic to the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, and is found naturally in three disjunct populations in Oklahoma, Georgia, and in Maryland and Delaware on the Delmarva Peninsula. In 2002, the three populations were recognized as subspecies 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 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.

Alnus maritima is considered a large shrub or small tree and is the only autumn-blooming member of its genus native to North America. All other North American alders bloom in the spring. The autumn-blooming phenology is a characteristic that Alnus maritima shares with two old-world Alnus species, Alnus nitida and Alnus nepalensis, which are endemic to southeast Asia. This profound similarity in their timing of anthesis has led to their classification as the only three members in the subgenus Clethropsis.

Source

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