Catalpa Invasive or Returning (Indigenous to North America):

The debate scientist has over the Catalpa genus is that these species could possibly have existed in North America prior to the last ice age and died off in North America during the Ice Age. Later after the Ice Age these species (Northern Catalpa and Southern Catalpa) migrated back to its native place of North America.[i] For proof of this, there was recent evidence that the Catalpa Speciosa fossil predates to the beginning of the last ice-age, found in the Mississippi valley.[ii] However, other scientist have suggested that the Catalpa as an invasive species. Despite this argument, if the Northern Catalpa and Southern Catalpa originated in the South, how can this species be able to adapt to an environment such as Montreal, where the temperature is around negative 25 degrees and still survive?[iii] Studying the Catalpa’s original history is difficult. There is not a lot of ‘popular research’ on these species.[iv] This could also be seen in the United States Forest Service and the Canadian Ministry of Natural Resource because those services have overlook or neglected these species.[v] For example, on the Canadian Ministry of Natural Resource website, the Catalpa species was searched; many things such as the G-rank, the S-rank or COSWIC status have a question mark or uncertainty. This shows that some areas of this species are still unknown to science.[vi]

The second aspect to consider is, if this species can eliminate or dominate over other biodiversities in the ecosystem. According to Sue Sweeney, the Catalpa might have a tendency in growing really fast creating a lot of seed babies, however, evidence showed tree was no overcrowding of the area by the Catalpa Species[vii] It generally gives space and shares the environment with other species around them. Furthermore, the Catalpa tree is commonly invaded by many species such as porcelain vein or Catalpa Sphinx, which resulted in these invaders keeping the Catalpa tree from growing fast and multiplying because many of seed babies will die by these invaders.[viii] Some might consider the Catalpa ability of Allelopathy; which is the process of preventing a growth of a plant due to the release of bimolecular from another plant. The purpose of this is to limit the competition that surrounds the tree. The known researches, such as Sweeney, have suggested that only time Allelopathy becomes a problem when ‘…the trees is allowed to grow large pure strands’.[ix] Despite this fact, these trees rarely able to produce these strands.[x] Allopathic process has evolved to adapt to the environment where the tree is easily out competed if there is a dense population of trees. As a result, this evolution is a very effective way for the Catalpa species to survive, which can keep the balance of the ecosystem and prevent over population. Therefore, the Catalpa Species should not be an invasive species.[xi]

[i] Sweeney S. 2005. Catalpa: Great American and invaders. The Monday Garden 162 (2): 40 –51.

[ii] Vines R. A. 2004. Trees, shrubs and woody vines of the southwest. Austin: University of Texas Press. P. 926-927.

[iii] Sweeney S. 2005. Catalpa: Great American and invaders. The Monday Garden 162 (2): 40 –51.

[iv] Ryder J A. 1978. Honey glands on Catalpa leaves [Internet] [Cited 2008 October 28] 31 (2). 161 Available on http://www.jstor.org/stable/4060301

[v] United States Department of Agriculture: Natural Resources Conservation Service [Internet]. [updated 2008 October 11] United States: Department of Agriculture, Natural Resource Conservation Service; [cited 2008 October 26, 2008]. Available from http://plants.usda.gov/java/ClassificationServlet?source=profile&symbol=CATAL&display=31

[vi] _______. Nature`s Hill Nursey. 2008. Southern Catalpa [Înternet] [Cited 2008, October 23, 2008]. Available from http://www.naturehills.com/product/northern_catalpa.aspx

[vii] Sweeney S. 2005. Catalpa: Great American and invaders. The Monday Garden 162 (2): 40 –51.

[viii] Stephenson A G. 1982. The role of Extrafloral Nectaries of Catalpa Speciosa in limiting herbivores and increasing fruit production [Internet]. [Cited 2008, October 25, 2008] (63) 3. 663-669. Available from http://www.jstor.org/stable/1936786?&Search=yes&term=Catalpa&list=hide&searchUri=%2Faction%2FdoBasicSearch%3FQuery%3DCatalpa%26wc%3Don%26dc%3DAll%2BDisciplines&item=1&ttl=1770&returnArticleService=showArticle.

[ix] Sweeney S. 2005. Catalpa: Great American and invaders. The Monday Garden 162 (2): 40 –51.

[x] Sweeney S. 2005. Catalpa: Great American and invaders. The Monday Garden 162 (2): 40 –51.

[xi] Sweeney S. 2005. Catalpa: Great American and invaders. The Monday Garden 162 (2): 40 –51.