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OUR BRITISH JUNGERMANNIÆ.
BY MARGARET PLUES.
MTHERE is a group among our cryptogamous plants of
1 exceeding delicacy of structure and grace of form, which lack their due meed of observation from plant lovers. These are the Jungermanniæ, or Liverworts, constituting the main part of the family of Hepaticæ, the second section of the Calyptreæ of Mohr, divided by him from the Mosses, because of the want of an operculum or lid, the distinguishing mark in the moss group. These Jungermanniæ exhibit cellular structure to perfection. With a pocket lens you can see the transparent network of the leaves, and under the microscope they become most beautiful objects. No male organs are discovered; the seeds are extremely minute, they are mingled with elastic spiral threads, and contained in a receptacle of a round or oval form; when the seeds are ripe the receptacle bursts into four parts, and thus when empty appears as a minute brown cross. This receptacle is supported upon a foot-stalk of greater or less length, sometimes measuring but a few lines, and sometimes attaining the length of two or three inches; it is slender, colourless, and almost transparent, and resembles spun glass; the oblong cells of which it is composed appear like joints under the microscope. The stalk rises from a tubular perichætium or calyptra formed upon the stem, or frond; it varies in form, being sometimes entire at the mouth, and consisting simply of the tube, but more frequently torn and jagged, and often accompanied by sepal-like formations.
The Jungermanniæ are parted into two great divisions : those assuming a form such as we are familiar with in many sea-weeds, are called Frondosæ ; and those with distinct stem and leaves, rather resembling mosses in their growth, are named Foliosæ. These latter are subdivided into Stipulatæ and ex-Stipulatæ, according to whether or no there are rudimentary leaves, or stipulæ, under the stem, accompanying the true leaves.
During the damp, mild weather of this winter and early spring, I have amused myself by the constant search for Jungermanniæ. One wood, with many paths and a pleasant name—the Chase Wood-has been my hunting ground, if I may be permitted to use a term so at variance in meaning from what it formerly signified.
Imagine, then, a dull February day, with the roads two or three inches deep in mud, and most uninviting for pedestrians, a thick fog hanging over the meandering Wye and its adjacent meadows. Turn with me to yon wooded hill; even the deep lane with high banks of red sand, where the dying fern fronds droop hopelessly, and the mosses display their most brilliant green, is less dirty than the main road. The lane leads past a quarry, and then you enter the wood. Perhaps the trees do drip a little, but only in the lower part; the path ascends by rocky steps, it is wide enough to save any danger to the looped-up dress from the long grass at its edges, and as you rise higher and higher the atmosphere becomes clearer, Red rock, cropping out here and there, retains but little of its original form, for the mosses clothe it thickly about its base, and our friends the Jungermanniæ cling upon the damp bank beneath it. We find large leaves, or more properly fronds, lapping one over another, each rooted to the wet ground; this is one of the Frondose Liverworts, J. epiphylla (No. 13). Out of the substance of these fronds, a little cup or calyx has arisen, presently a tubular calyptra will spring from it, then a long transparent stalk, bearing the round receptacle, which will burst into a cross of four broad valves. The fronds are dark green, shaded with brown or purple in the centre. This Liverwort is a common object, not only in our woods, but on damp garden walks, and even on flower-pots in wet places. A closely allied species, with fronds curled at the edges, and of a paler hue, flourishes about a small spring in the same wood; its large white calyptræ, and the narrow segments into which the receptacle splits, are clear marks of distinction : J. pinguis (No. 12). Clustering about the tree roots, and sometimes growing in patches on the lower part of the bark, you find the slender fronds of the J. furcata (No. 11). Its pale green hue attracts the attention, and its crowded fronds have a mossy appearance ; it is only when you stoop to examine it closely that you recognize their strap shape.
Nearing the top of the wood, splendid blocks of puddingstone guard the path on either side. Here it well repays the botanist to take out his glass, and examine the plants on the southern surface. I could name half a dozen mosses, and nearly as many lichens, as well as several ferns, among those rock dwellers; but I must restrict myself to Jungermanniæ. To begin at the base, where the mosses grow thick, we find interlacing amongst them the familiar branches of the J. Asplenoides, the largest and most frequent of the Leafy Liverworts (No. 1). This plant is rare in fruit, but its long branches, with their outspread rows of horizontal leaves, pale green and glittering, are to be seen on every damp hedge-bank or shady copse. The slender J. bidentata grows under that rock
also, its foliage still paler, its stems tender in the extreme; it is slightly branched, its calyx and calyptra are large in proportion to the rest of the plant, and deeply cut; the footstalk is long and the receptacle oval. The fruit was formed, but not opened in February (No. 6). Higher up the rock, but also sheltered by mosses, flourish the minute but sturdy stems of the J. obtusifolia (No. 10). These stems are not branched, and stand almost upright. The leaves are divided into two rounded lobes; the smaller is turned in front of the stem, and the larger wraps round to the back, thus giving the appearance of two rows of leaves on either side the stem. The fruit springs from the end of the stems, but it does not appear till much later in the year. Ascending yet higher on the rock, to a level with your own shoulder, you find a still more minute Jungermannia covering the stone in filmy patches of pale green. This is the J. reptans (No. 7); it is a fairy-like plant, its main stem and plentiful branches only occupying about a quarter of an inch. The lens shows the leaves to be placed alternately on either side the stem, each cut into four sharp points. A paler film, studded with minute oval objects, which prove on examination to be calyptræ, and from which issue numerous glassy threads, bearing a forest of microscopic brown crosses, proves to be a patch of J. connivens (No. 3); every tiny leaf standing forth as a perfect crescent under the microscope, though the naked eye can hardly distinguish the perfect plant from an Alga, except the fructification be present.
The trees form favourite habitats for the Jungermanniæ. In the Chase Wood we find not only the J. furcata on the bark near the roots, but large patches of a closely interlaced Liverwort. On this mild February day the foliage is a bright green; the forked branches bear calyptræ on their summits, from whence issue very short foot-stalks bearing slightly oval receptacles; or, if these have burst, crosses of four blunt valves. This is the J. complanata (No. 4). Upon the same tree possibly, or failing that, on a very near neighbour, Liverwort patches of a very different hue are flourishing and displaying their seed-vessels. The overlapping leaves, with their rounded forms and unbroken margins, show an affinity with the J. complanata ; but a marked difference will be seen on applying the lens, for beneath each leaf is a rounded stipule, proving it to belong to the Stipulatæ division of the foliaceous group. This Jungermannia spreads in wide patches, generally of a reddish hue: J. dilatata (No. 8).
The wood grows thicker, and we find ourselves descending between oozy banks of red earth. Here a partial greenness tempts us to a closer inspection, and we recognize tiny crosses of warm brown. We feel sure we have got a Jungermannia, hut we must apply the lens before learning its form. The