Wednesday, August 20, 2014

Christmas in mid-August

And why not Christmas in August? In my opinion any day a person discovers a cool plant or animal new to them feels like Christmas.

On this particular day I was searching for odonate naiads in a a sand-bottomed woodland stream near the intersection of the trans-Canada Trail and Sulphide Road (44.494167°, -77.285556°). I happened to look up, and growing on a shaded rocky bank covered with thin soil was a luxuriant patch of (what else?) Polystichum acrostichoides, better known as Christmas Fern.

A lower and upper surfaces of a fertile frond – only the pinnae toward the tip produce spores. The two lowest pinnae are angled downward.

A closer look at the dense clusters of sori.

The pinnae (note the bristly margins) have upward pointing lobes near their bases, think of the toe on a Christmas stocking.

The stipe and rachis are scaly.

The dark green glossy leaves – both the sterile fronds and non-reproductive parts of the fertile fronds – persist throughout the winter, always a welcome break from the monotonous white of a winter's day. Although there are other fern species with evergreen fronds, for whatever reason this one earned the name Christmas Fern.