Their general effect must have been eminently picturesque. A shaggy covering of green spiky leaflets bristled over their multitudinous pendant boughs; and where on the older stems these leaflets had decayed and dropped off, the outer bark was laid bare, fretted over with rows of diamond-shaped or oval scars, separated by waving lines of ridge or furrow, that wound spirally round the stem. From not a few of the branches there sprang oblong hirsute cones called _lepidostrobi_ (Fig. 11), which bore the sporangia, or seed-cases. These cones are of frequent occurrence in the shales of the coal-measures, and may be readily recognised. They had a central axis round which the oblong sporangia were built, the whole being protected externally by a thick covering of pointed scales, imbricated like the cone of the Scotch fir. The leaflets of lepidodendron, called _lepidophylla_, were broader than those of the Scotch fir, and had a stout mid-rib, which must have given them a rigidity like that of the araucarian pine a plant they may also have resembled in the dark glossy green of its leaves. [Footnote 19: See Hooker, _Mem. Geol. Surv._ vol. ii. part ii. p. 436.] [Illustration: Fig 10. Lepidodendron Sternbergii.] [Illustration: Fig. 11. Lepidostrobus.] Of all the common coal-measure plants, there is perhaps none so abundant as that known by the name of _stigmaria_, or punctured-stem. It is found spreading out its rootlets for several yards in beds of shale and under-clay, and sometimes even limestone,[20] while, in many sandstones, fragments of its blackened stems lie as thickly strewn as twigs among the woods in autumn. I have said that several of the plants above described have greatly puzzled botanists. None of them, perhaps, has given rise to so much conjecture and variety of opinion as the stigmaria. The history of the discussion regarding its nature and affinities, would be not a little interesting as an illustration of the slow hindered progress often attendant on the researches of science, and an instance of how a few simple facts are sometimes enough to overturn the most plausible theories and probable conjectures. Many thousands of specimens had been examined ere one was found that revealed the true nature of the stigmaria. It was by some imagined to be a soft succulent marshy plant, consisting of a number of long branches radiating from a sort of soft disk, like spokes from the centre of a wheel. Analogies were suggested with dicotyledonous tribes, as the _cacti_ and _euphorbiæ_, though it was at the same time admitted that the ancient plant presented appearances which seemed very anomalous. [Footnote 20: The fresh-water limestone of Mid-Calder abounds in long trailing stems and rootlets of stigmaria, mingled with other terrestrial plants, and shells of _cyprides_.] [Illustration: Fig. 12 Stigmaria rootlets springing from Sigillaria stem.]