Many common plants are dicots, and have a similar form of initial growth in which the seed splits and the two halves form the first two leaves.

Most ferns also have a specific growth form: they emerge from the ground in a spiral, called a fiddlehead. That shape is the adornment on a violin above the tuning pegs. Or a crosier, the top of a bishop's staff. Where do you suppose the violin makers got the idea for that design? Only ferns emerge in that pattern, though some other plants have tendrils that uncoil.

The term fiddlehead has a very specific meaning in the grocery trade. It refers to the emerging shoots of Ostrich fern (Matteuccia struthiopteris), the only fern species deemed safe to eat in North America. At least some other ferns have too many chemical defenses. But in discussing ferns in general, fiddlehead is just the stage of growth as the stalk is still uncoiling.

The shape is actually a logarithmic spiral, and the relative dimensions stay the same as it grows larger. The shape is defensive, to protect against e.g. insects eating the tender growth tip at the center. Ferns don't have a mechanism for secondary growth, like a tomato with new growth sprouting from the "shoulders" where the branches come off the main stem. Part of what makes ferns pretty is that they retain the symmetry of their design. If they do lose their growth tip, they have to just grow another frond instead.

Besides hiding the growth tip at the center of the spiral, ferns often protect the outer tissue with armor of hairs or scales. These often persist through the growing season and are a clue to help identify the species, if you look at the lower part of the stem. Most fiddleheads are green, but Royal ferns are purple, and Cinnamon ferns can be blue or even reddish. In evergreen ferns like Christmas or Polypody or Marginal Wood fern, they will emerge from a bed of last year's fronds . Look for them protruding, clad in white hairs, from the supine dark green fronds of a Christmas fern. Sensitive or Ostrich or Netted Chain fiddleheads will emerge among the standing fertile fronds from last year.

Ferns are perennial (a useful trait in the garden) and most emerge quickly in early spring. Some have an indefinite lifetime; individual plants can be more than 100 years old. They don't have bulbs, but store energy in their rhizome, the underground portion of the plant. In my yard, most species emerge in April, and it is a joy to walk around the house to see what else has appeared overnight. Since I mark their locations I can find them as soon as they emerge. In the woods I might miss the smallest new shoots, but by late April there should be enough larger plants to reward a fiddlehead hunt. Don't eat them though; Ostrich ferns are rather uncommon around here.

Cinnamon fern
Marginal Wood fern

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