Thoreau tells us, “Nature made a fern for pure leaves.” Fern leaves are in the highest order of cryptogams. Like those of flowering plants they are reinforced by woody fibres running through their stems, keeping them erect while permitting graceful curves. Their exquisite symmetry of form, their frequent finely cut borders, and their rich shades of green combine to make them objects of rare beauty; while their unique vernation and method of fruiting along with their wonderful mystery of reproduction invest them with marked scientific interest affording stimulus and culture to the thoughtful mind. By peculiar enchantments these charming plants allure the ardent Nature-lover to observe their haunts and habits.
“Oh, then most gracefully they wave
In the forest, like a sea,
And dear as they are beautiful
Are these fern leaves to me.”
As a rule the larger and coarser ferns grow in moist, shady situations, as swamps, ravines, and damp woods; while the smaller ones are more apt to be found along mountain ranges in some dry and even exposed locality. A tiny crevice in some high cliff is not infrequently chosen by these fascinating little plants, which protect themselves from drought by assuming a mantle of light wool, or of hair and chaff, with, perhaps, a covering of white powder as in some cloak ferns—thus keeping a layer of moist air next to the surface of the leaf, and checking transpiration.
Some of the rock-loving ferns in dry places are known as “resurrection” ferns, reviving after their leaves have turned sere and brown. A touch of rain, and lo! they are green and flourishing.
Ferns vary in height from the diminutive filmy fern of less than an inch to the vast tree ferns of the tropics, reaching a height of sixty feet or more.
Ferns are propagated in various ways. A frequent method is by perennial rootstocks, which often creep beneath the surface, sending up, it may be, single fronds, as in the common bracken, or graceful leaf-crowns, as in the cinnamon fern. The bladder fern is propagated in part from its bulblets, while the walking leaf bends over to the earth and roots at the tip.
[Illustration: MALE SHIELD FERN. Fern Reproduction by the Prothallium]
Ferns are also reproduced by spores, a process mysterious and marvellous as a fairy tale. Instead of seeds the fern produces spores, which are little one-celled bodies without an embryo and may be likened to buds. A spore falls upon damp soil and germinates, producing a small, green, shield-shaped patch much smaller than a dime, which is called a prothallium (or prothallus). On its under surface delicate root hairs grow to give it stability and nutriment; also two sorts of reproductive organs known as antheridia and archegonia, the male and female growths analogous to the stamens and pistils