Wednesday, May 7, 2008


Polystichum acrostichoides
, or the Christmas Fern, is a very common species in forests throughout the east and midwest. It remains evergreen through the winter (hence the name), and so can be seen throughout the year, if you're willing to dig through some snow. However, it appears at its best when new fiddleheads come up in spring. They are covered in white to golden scales, and are frequently quite acrobatic, like the one pictured at lower right, which was doing some interesting flips and curls as it unrolled. The specific epithet, acrostichoides, derives from the fact that this fern has acrostichoid sori, meaning they are spread across the lower surface of the pinnae rather than grouped into little clumps. The fertile pinnae are only found at the tips of the fronds, while the rest are sterile and do not develop spore-bearing structures. Another feature that makes Polystichum easy to recognize is the the little ear-shaped part of the leaf, the auricle, found next to the rachis on the upper edge of each pinna.

1 comment:

Anonymous said...

oh, so that's what they are called, i've been wondering for a time now what kind of plants are growing in our neighbor's yard.

Poulsbo flowers