BOTANY. 65 
high, which give a peculiar character to the landscape. The theca of ferns 
has been looked upon as a modified leaf, having the same gyrate or circinate 
development as the frond. Leaves have occasionally been produced in place 
of thecze. Ferns having the thec on the back of the frond, and furnished 
with an elastic rmg or band, are called dorsiferous and annulate ; while those 
having no thecal ring are exannulate. 
Few of the ferns are used medicinally. They are in general demulcent 
and astringent. Some yield food. The rhizome of Lastrea Filix mas, 
Male-shield-fern, has been used as a vermifuge, especially in cases of 
tape-worm. It contains starch, gum, saccharine matter, tannin, green 
fixed oil, and resin. Its properties are ascribed to the fixed oil. The 
rhizome has been used for tanning, and its ashes contain much carbonate 
of potash. The syrup called capillaire, and certain pectoral mixtures, are 
prepared from Adiantum pedatum and A. Capillus Veneris. The rhizome 
of Pteris esculenta is used as food in Australia, and that of Marattia alata 
in the Sandwich Islands. Many other species of Ferns are esculent. The 
stems and leaf-stalks of Ferns are often covered with scales and with woody 
matter. One (Davalia canariensis) is called Hare’s-foot Fern on this 
account ; and another (Aspidium Baromez) receives the name of Scythian, 
or Tartarian-lamb, because, when prepared in a particular way, it resembles 
that animal. 
Sub-order 1. Daneea. Thece united in masses, exannulate, opening 
irregularly by a central cleft. Ex. Danza. . 
Sub-order 2. Ophioglossee. 'Thece collected, into a spike, formed at the 
edges of an altered frond, distinct, exannulate, two-valved. Examples, 
Ophioglossum, Botrychium. Ophioglossum vulgatum (pl. 54, fig. 57), very 
rare in the United States, Botrychium lunaria (fig. 56). 
Sub-order 3. Osmundee. Thece dorsal, or forming a separate stalked 
mass (an altered frond), distinct, with a terminal or dorsal ring, more or less 
incomplete, bursting lengthwise by a regular slit. Examples: Osmunda, or 
flowering fern, O. regalis (pl. 54, fig. 55). 
Sub-order 4. Hymenophyllee. Thece marginal or dorsal, nearly sessile, 
distinct, annulate, ring horizontal, complete, sometimes oblique, bursting 
lengthwise. Examples: Hymenophyllum, Trichomanes, Lygodium. 
Sub-order 5. Polypodinee, or true Ferns. Thece on the back of the 
frond, pedicellate, or sessile, distinct, annulate, ring vertical, usually 
incomplete, bursting irregularly and transversely. Aspidium filix mas 
(pl. 54, fig. 50): a, a frond; 6, rhizoma; c, part of a frond, with sori ; 
d, the indusium; e and f, closed and open thece. Adiantum capillus 
veneris (fig. 54a); 6, portion of the frond with sori; c, opened theca. 
’ Lomaria spicans (pl. 54, fig. 53); a,a fertile, and 6, a sterile frond; c, a 
portion of a frond, with sori; d and e theca. Asplenium trichomanes 
(fig. 51 a); 6b an opened theca. Scolopendrium officinarum (fig. 52); 
a, a frond; 6, a section magnified, showing two longitudinal sori; c, an 
opened theca. This species is found in the western part of New York. 
Polypodium vulgare (fig. 49°); a, frond; 6, rhizoma, with a frond stalk ; 
c, portion of frond magnified; d, magnified sorus; e, theca; f, the same 
ICONOGRAPHIC ENCYCLOPADIA.—VOL, Il. 5 65 
