Sunday, March 24, 2013

Swamp Jessamine - Gelsemium rankinii

Swamp, or Rankin's, jessamine (Gelsemium rankinii) is a wetland version of the more ubiquitous yellow jessamine (G. sempervirens). In fact, the two species would be very difficult to tell apart were it not for the types of habitat they occur in.  Swamp jessamine is a wetland specialist and occurs in bogs, acid swamps and floodplain forests.  Yellow jessamine is most often encountered in dry uplands.  There are other noticeable differences if you catch the plant in flower or seed.  Swamp jessamine is not fragrant.  The seeds do not have noticeable wings, like yellow jessamine does, and the calyx (the old sepals of the flower bud) persists on the base of the fruit.
Swamp jessamine is the only jessamine you might encounter in a swamp.  This is a north Florida species and is present only in the Panhandle counties as well as Hamilton and Nassau Counties along the Georgia border.  It also occurs in the states of the Southeast Coastal Plain - from Louisiana to North Carolina.
Like its close cousin, swamp jessamine is an evergreen vine without tendrils. It climbs throughout the adjacent vegetation by twining up and over it.  The lanceolate leaves are opposite each other on the stems.
Blooming occurs in late winter/early spring.  These photos were taken on March 8 in Tate's Hell State Forest, Franklin County.  The blooms are a rich yellow, but without the characteristic fragrance that makes yellow jessamine so spectacular as a home landscape plant.  Despite this, they are visited by much the same pollinators.
Swamp jessamine has not been offered by nurseries associated with FANN - the Florida Association of Native Nurseries.  I do not have experience with it in my landscape and do not know how adaptable it might be to non-wetland conditions or regions of the state outside its natural range.  This is a beautiful wildflower for wetland sites in north Florida.  For other situations, yellow jessamine is a better choice.

1 comment:

  1. I have often wondered why the jessamine in my yard has no scent - now I know! I live in Hamilton County and it grows along the road to our house. It is swampy or boggy except during the driest times of years. It is growing in normal soil in my yard and has to be cut back every year or it will take over the yard. I was told it was Gelsemium sempervirens, but now I think it is probably G. rankinii. Oh, the reason I was researching this one is that a local box store has it for sell.


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