Fern Terms

Axis:   (or Rachis) is that part of stem carrying the leaflets.  Similarly, where over-all leaf is simple that part of stem contained by leaf's surface is called the Midrib, the name also applied to central stems contained by leaflets, subleaflets, and lobes.

Leaf:   (Frond, or Blade) is the flat, green, expanded part.  Leaves vary in size and shape according to species.  Some species have different sizes and shapes for fertile and sterile leaves.  Fern Leaves not only perform function of photosynthesis, but fertile leaves bear, usually on undersides, the spores for reproduction, a function typical to ferns.  Leaves vary by species from a simple undivided form to compound and decompound forms with laciness so characteristic of ferns in general.

Leaflets:   When leaf is compound, divisions are known as Leaflets, or Pinnae, and leaf as whole is Once-cut, or Pinnate.  When Leaflets are decompound, subdivisions are known as Subleaflets, or Pinnules, and leaf as whole is Twice-cut, or Bipinnate.  When Subleaflets are divided again, divisions are known as Lobes, or Pinnulets, and over-all leaf is Thrice-cut, Lacy-cut, or Tri-pinnate.

Roots:   Usual root forms are thin, wiry, black, forking, shallow-creeping, and grow from sides and undersides of rootstock.

Rootstock:   (Stock, Trunk, or Rhizome) supports roots below and stems and leaves above.   Either short and thick, and almost completely buried, with only the growing parts of stems and leaves ascending in short trunks above ground, or (the more typical Rootstocks, better called Rhizomes) elongated, narrow, or thin, and growing horizontally below or on the surface of ground, with stems and leaves sprouting at intervals from upper surfaces of Rhizomes.  Rootstocks perennial; stems and leaves stocks usually covered with scales or hairs.

Stalk:   (Stipe, or Stem) supports the leaf.  Usually flat or concave in front, with rounded back, and covered with hairs or scales (particularly when young), of various shades of tans, browns, silvers, and black.  Arrangements of Stalks growing from root-stock, whether in circles, pairs, individually, or in tufts, vary with genus or species.

Stem:   supports leaf below axis, and similarly is the support for subleaflet or lobe.

Veins:   Venation of fern leaves is an important distinguishing characteristic of the various species and genera.  Position of spore case on underside of leaf and its relation to life-bearing Veins often identify the species.

Terms Wrom: VTLBXFGGMEPYOQK Boughton, A Field Guide to the Ferns, Houghton Mifflin Company, Boston, 1956]