Fiddleheads

Although the sun is shining brightly at the moment here in Madison, my computer tells me it's 5 degrees outside. I think many people are starting to feel a hankering for spring and some semblance of warmth in the outside world, and for me one of the most welcome signs of spring (besides the crocuses) will be new ferns. When new fern leaves emerge, they are typically rolled up in these familiar fiddleheads, also called croziers, which slowly unfurl to reveal the delicate architecture of the fronds.

This unfurling process of the tightly-curled leaf is called circinate vernation. Circinate refers to the circular or ring-shape of the fiddlehead, and vernation comes from 'vernal' (meaning 'spring'), when new leaves tend to emerge. By remaining tightly rolled up, the growing tip of the leaf is protected during emergence, and this protection is often supplemented by thick hairs or scales that cover the fiddlehead, as you can see in some of these photos. You can also see that the lateral leaves are in fiddlehead-form too, just as the tip is.

Thelypteris

We saw lots of Theylpteris in Costa Rica; these are two species of Thelypteris subgenus Goniopteris. The subgenus is characterized by the basal pinnule veins, which come together where neighboring pinnules meet (this is very clear in the left-hand picture). Technically these leaf divisions aren't really pinnules, since the blade isn't divided all the way to the costa (the midrib of each major leaf division; the costa is the strong rib visible towards the right side of the right-hand picture), but it's convenient to characterize them that way.

Thelypteris is a common fern in North American woods and wetlands. Thelypteris palustris, the marsh fern, and Thelypteris novaboracensis, the New York fern, are pretty typical-looking ferns that most people have probably seen but not really noticed...

Nephrolepis

I have returned from the beautiful, balmy mountains of Costa Rica to the frozen hellscape of Madison, WI, where during my absence there was a week when the temperature didn't go above 8 degrees Fahrenheit. Glad I missed that, although today's -1 isn't proving too pleasant either. Given the bone-numbing weather I find myself pining for Costa Rica's beautiful ferns, so I will focus on them for a few posts.

This beauty is a species of Nephrolepis, a genus in Polypodiales that is characterized by, among other things: an apex that remains curled in a fiddlehead, and articulate pinnae that fall off the rachis. The popular house plant Boston Fern is a species of Nephrolepis, but it tends to leave a mess behind when it decides to shed its pinnae. This one was growing as an epiphyte in a rainforest preserve, called Braulio Carrillo, which we visited on the return trip from La Selva to San Jose.

Campyloneurum

In this inaugural blog post, it seems appropriate to talk about the fern I've chosen for my header image. It is a species of Campyloneurum from Costa Rica, where I'm currently taking a course on Tropical Ferns & Lycophytes through the Organization for Tropical Studies, a consortium of colleges and universities from around the world.

Campyloneurum is a genus in the Polypodiaceae, and this species was collected at Las Cruces Research Station, which is maintained by OTS near San Vita, Costa Rica, close to the Panamanian border. Campyloneurum is an epiphyte with simple, entire leaves, veins that form a net (said to be anastomosing), and round sori that lack the covering called an indusium which is found over each sorus in many ferns. In this picture each large round clump is a sorus, and the smaller orange glassy-looking things that are piled up to make it are the sporangia. These contain the spores, and they will dry and split open when the spores are mature and ready to be dispered.