Eryngium prostratum and the November Lake Shore

November at the Falls Lake State Recreation Area has brought crystal clear, sunny days and cold nights, with several hard freezes.    The smaller plants along the lake shore, especially in protected inlets, are in a final blooming period before entering dormancy.  Perhaps the hardiest of this lake shore community is Eryngium prostratum – Creeping Eryngo – which prefers the very edge of the water with all its challenges.  Eryngium prostratum is a member of the carrot family (Apiaceae) and is a perennial.  Colonies can reproduce  vegetatively  by extending creeping horizontal shoots, which then root at the nodes and produce new plants.  Under favorable growth conditions, plants can even form tangled mats that cover parts of the shoreline.  But the large jumps in population seem to come from the germination of profuse numbers of seeds.

After a recent dry spell, the water level of Falls Lake has dropped, exposing large bands of sand and mud flats.  Huge numbers of seedling E. prostratum can be seen dotting the mud and sand, looking a lot like stranded Duckweed from a distance.

Eryngium prostratum seedlings

Eryngium prostratum seedlings

The seedlings and the initial leaves are very small.

Eryngium prostratum seedlings

Eryngium prostratum seedlings

Small colonies that germinated at different times often mix together.

Eryngium prostratum

Eryngium prostratum

As the plants grow, symmetrical basal rosettes are formed.

Eryngium prostratum Basal Rosettes

Eryngium prostratum
Basal Rosettes

As new leaves are added, leaf shape begins to change and elongate, and notches appear.  A few plants begin to show fall purple colors.

Eryngium prostratum Older Basal Rosettes

Eryngium prostratum Older Basal Rosettes

Mature plants can still be found in full bloom.  The flowers are either blue or white.

Eryngium prostratum Flowers

Eryngium prostratum Flowers

Last November, one year ago, this area was vastly different.  The lake level had been lower during the summer and heavy fall rains brought the water level up, submerging large numbers of E. prostratum that had formed along the shore.  The plants persisted for many weeks under water but eventually the sustained higher level of the lake caused the loss of most of the plants in the deeper water.  The blanket of tiny seedlings pictured earlier now covers this formerly submerged area.

Eryngium prostratum Submerged Colonies

Eryngium prostratum
Submerged Colonies

The colonies of E. prostratum at Soapstone Cove, below Rockcliff Farm, have diminished greatly over the past several years due to severe bank erosion.  The remaining plants can sometimes be found hanging down the vertical, eroded bank, suspended by their shoots like cliff climbers by their safety ropes.   The eroded banks seem to be one hurdle that the diminutive plants can not easily overcome.

Eryngium prostratum Hanging Down a Vertical Bank

Eryngium prostratum Hanging Down a Vertical Bank

Herb Amyx

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