Key to the Common Ferns of Maryland

Prepared by Dwight Johnson, revised 2014

Downloadable version of the key in pdf

1. I. Broadest at Base
   • Once cut with wavy pinnae ..... Sensitive Fern
   • Twice cut with wiry stipe ..... Broad Beech Fern
   • Thrice cut
     1. i. Large, coarse; usually more than one plant in area; not lacy ..... Bracken Fern
     2. ii. Small and growing singly or in a small group; delicate and lacy
        1. A. Fertile stalk arising from center of plant; on lowest pinna, the pinnule closest to the stipe is shorter than the next pinnule ..... Rattlesnake Fern
        2. B. Fertile stalk arising from base of the plant; on lowest pinna, the pinnule closest to the stipe is longer than the second pinnule ..... Cut-leaved Grape Fern
2. II. Fully Tapering to the Base
   • Once cut
     Small-medium size; very narrow frond; pinnae oblong with "boot" similar to Christmas Fern; stipe smooth and dark ..... Ebony Spleenwort
   • Twice cut
     1. i. Large and growing in a definite crown; fertile frond (if present) in center, found more often in gardens ..... Ostrich Fern
     2. ii. Medium size, and growing zig-zag over an area, not in crowns ..... New York Fern
3. III. Semi-tapering to the base
   • Once cut
     1. i. Pinnae two inches or less
        1. A. Boot-shaped pinnae attached by a short stalk ..... Christmas Fern
        2. B. Pinnae with no stalk; usually growing on top of rocks ..... Common Polypody
     2. ii. Pinnae over two inches long, wavy (resembles Sensitive Fern), found in moist areas east of I-95 ..... Netted Chain Fern
   • Twice Cut
     1. i. Stipe with brown scales; sori on edge of pinnule ..... Marginal Wood Fern
     2. ii. Stipe smooth or slightly hairy
        1. A. Large size; woolly tufts at bases (axes) of pinnae ..... Cinnamon Fern
        2. B. No tufts at axes
           1. Large size; some pinnae apparently missing from middle of fertile fronds (if present); veins in pinnule forked ..... Interrupted Fern
           2. Sori and pinnule veination in herringbone pattern; 2 lowest pinnae pointing outward in a V shape ..... Silvery Glade Fern
           3.  Growing zigzag in patches near wet areas; common east of I-95 ..... Marsh Fern
           4. Large and shrubby; leaf-like pinnules with short stems ..... Royal Fern
   • Thrice Cut
     1. i. Stipe with brown scales at base
        1. A. On lowest pinna, the pinnule closest to the stipe is clearly longer than the second pinnule ..... Spinulose Wood Fern
        2. B. On lowest pinna, the pinnule closest to the stipe is about the same length or shorter than the second pinnule ..... Intermediate Wood Fern
     2. ii. Stipe smooth
        1. A. Growing in a clump; sori slightly curved and in herringbone pattern; rachis smooth, not hairy ..... Lady Fern
        2. B. Growing zig-zag over area; hairy rachis; sori small and round ..... Hayscented Fern
        3. C. Pinnules lobed (leaf-like); stipe long and slender ..... Fragile Fern
     3. iii. Stipe and rachis hairy, pinnules lobed; lower pinnules rounded, small fern found growing in rocks ..... Blunt-lobed Woodsia
4. IV. Unique Shaped Fern
   • Circular-shaped fronds with pinnae on outer rim of stalk; dark wiry stipe ..... Maidenhair Fern
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