Thursday, February 16, 2012

Plant Profile: Black Mangrove (Avicennia germinans)

This post is one of a series from Botany professor Nisse Goldberg's students at Jacksonville University. Student authors: Shari Dillet, Devin Resko, Jonathan Kelly

Mangroves are found in Florida because of its sub-tropical environment. The humid, coastal regions of Florida offer ideal conditions for the black mangrove (Avicennia germinans). This particular tree can be seen along the intertidal salt marshes of St. Augustine down to the Keys. The increasing water temperatures of the Atlantic have contributed to the mangroves range expansion northward along the east coast of the U.S.

Avicennia germinans wood is a dark brown with square scales that aids in protection against harsh winds. Its leaves are 2-4 inches in length by 1 inch in width. The topside of the leaf is smooth and glossy while the bottom side is fuzzy. The black mangrove can grow up to 50 feet tall in Florida regions but that is rare. In Louisiana, the mangrove only reaches heights up to ten feet.


Figure 1. a. black mangrove. b. red mangrove. Photo credit: A. Tappert. http://en.wikipedia.org/wiki/File:Black_mangrove-everglades_natl_park.jpg; http://en.wikipedia.org/wiki/File:Red_mangrove-everglades_natl_park.jpg
The black mangrove has unique aerial roots called pneumatophores (Figure 1). Pneumatophores pop up around the base of the tree and provides a means to access oxygen from aboveground. Typically, the saturated soils are low in oxygen. By comparison, the red mangrove uses prop roots for similar purposes (Figure 1).
The specific epithet germinans refers to the seed germination process. Referred to as vivipary, the juvenile seed of the black mangrove matures and grows during the time it is attached to its parent tree. After the juvenile seed falls off the parent, it will float for a period of time, and then settle. At this time, the roots will begin to ‘germinate’.

The black mangrove is ecologically important for a number of reasons. It takes up nutrients that run off into salt marshes. Also, it traps sediments from the brackish waters and builds banks, which prevents erosion. Mangrove forests are a haven for several species of birds such as, the Reddish Egret (Egretta rufescens) and the Yellow Crowned Night Heron (Nyctanassa violacea). In June and July, bees take up nectar from the mangrove’s blooming flowers and their hives can be harvested for fine-quality honey.
The plant can be purchased from vendors at this site: http://www.floridanativenurseries.org/plants/detail/avicennia-germinans
Work Cited:

1. Houck, M. (2009). Black mangrove Avicennia germinans. United States Department of agriculture Natural Resources Conservation Service, Retrieved from http://plants.usda.gov/factsheet/pdf/fs_avge.pdf

2. Hill, K. (2009). Mangrove habitats. Smithsonian Marine Station at Fort Pierce, Retrieved from http://www.sms.si.edu/irlspec/Mangroves.htm

3. Gann, G., Abdo, M., Gann, J., & Gann, G. (2005). Black mangrove. Natives For Your Neighborhood., Retrieved from http://regionalconservation.org/beta/nfyn/plantdetail.asp?tx=Avicgerm

 
Also see our previous post: Florida's Marvelous Mangroves

1 comment:

Anonymous said...

The trees are called viviporous.