Monday, August 23, 2010

Large Yellow Lady's Slipper (Cypripedium parviflorum var. pubescens)

Previously known as Cypripedium pubescens, the Yellow Lady's Slipper is one of the best known of our native orchids and that for several reasons.  It is found in nearly every US state and every Canadian province.  It is also one of the few native orchids that can be cultivated in a garden, though it must immediately be added that the plants can be purchased from reputable nurseries and there is, therefore, no need to dig them up from the wild and so destroy them in their native habitats.


There is a great deal of disagreement about this species, its name and its varieties.  Some still prefer to use the older name, others disagree as to the number of varieties of this species.  We ourselves have identified the plants shown below as variety pubescens, but never having seen variety makasin, which also grows in our area, we have to admit that this is an educated guess.

The differences are supposed to be:
1) the scent - var. makasin having a much stronger scent than pubescens;
2) the amount of pubescence or hairiness on the upper bract (the leaf-like structure behind the flower) - var. pubescens being much hairier;
3) flower size - var. makasin being smaller than pubescens;
3) flower color - var. makasin being more richly colored.
But many of these features overlap, making exact identification difficult.


The plants we have seen have been growing in open forest, in the flood-plain below a mountain lake, but always under the shelter of brush and small trees), and along a river or lakeside.  They seem to prefer some shelter from direct sunlight and moister areas.


Flower color has varied considerably in the plants we've seen, the color of the petals from a pale greenish yellow to a brownish mahogany, of the pouch from a pale to a very deep yellow, sometimes with pale stripes, and of the staminode (the shield-like structure at the opening of the pouch) from a plain yellow to yellow spotted red.  Flowers are around 10 cm in size with a pouch about 5 cm.


We have found them in several locations growing in large clumps, with as many as 50 flowers in the clump and scattered through the woods by the hundreds or thousands.  We have never seen more than two flowers on one stem, though they are reputed to carry as many as four.  The plants vary in size up to 60 cm and have four or five pleated leaves that make the plant recognizable even when without flowers.


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