The MARATTIACEÆ may be partly known by their huge globose rhizome projecting above the ground, and rough with the processes from which the leaf-stalks have fallen. This sends out a few large fibrous roots, and consists of cellular tissue abounding in starch, with small bundles of fibro-vascular tissue regularly distributed through it. The stipes have a pair of stipule-like organs at their base; and the sori are either oblong fronds of a double row of sporangia, which in some cases is concrete, or they are circular with the sporangia annularly concrete, or they are connate throughout the fertile portions. These peculiarities respectively distinguish the smaller groups of Marattineæ, Kaulfussineæ, and Danæineæ, while the group Marattiaceæ itself is distinguished from Ophioglossaceæ by having its sori dorsal, that is, set on the back, or under-surface, of flat leafy fronds. The leaves of Angiopteris evecta are used as a perfume in the Sandwich Islands, and its rhizome serves for food, as that of the Marattia salicina does in New Zealand. The OPHIOGLOSSACEÆ, or Adder’s Tongue ferns, are few in number, and present comparatively little difference in structure. They are known among the exannulate series, from the Marattiaceæ, by having their fertile fronds contracted, bearing their sporangia at the margin, so that being entirely occupied by sporangia, the fertile fronds appear as if they were an inflorescence distinct from the foliaceous organs, as indeed they are analogically. In this group there is the further difference that the fronds are not circinate, but straight, in their æstivation. These Adder’s Tongue ferns are dwarf herbaceous plants, differing greatly in structure from the true ferns, though there is some similarity to them in the fructification. They are divided into four genera, of which Ophioglossum and Botrychium are best known. The base of the stem is thick and bulbiform, and sends off spreading succulent roots. The species of the genus Ophioglossum are chiefly plants of a warm climate, but Ophioglossum vulgatum, or common Adder’s Tongue, is distributed in almost every part of the globe. In England it is exceedingly abundant in meadows and pastures, and varies in height from a few inches to a foot, in moist soil. It has one barren ovate and one fertile linear frond. The barren frond, which is of a yellowish-green colour, invests the stem of the fertile frond like a spathe; its form is ovate, varying to ovate lanceolate, and more or less obtuse, with a complicated network of anastomosing veins. Bivalved sporangia form two parallel series on the margins of the club-like terminations of the fertile frond. Soon after the fruit is shed the fronds die, but one or two buds are previously formed at the base of the plant, which remain dormant till the following spring.[74]