Equisetum

“ I. Equisetales.—The plants of the single living genus Equisetum, which vary in height from a few inches to 40 ft., have subterranean rhizomes, from which the erect shoots arise. The habit of the plant depends on the degree of branching rather than upon the foliage. The internodes are elongated and hollow. The leaves are borne in whorls, those of each whorl cohering, except at their extreme tips, to form a sheath. The leaves of successive whorls alternate with one another, and this applies also to the branches which arise in the axil of the leaf sheath. ”

“ Nothing is known of the structure of the fossils beyond the character of the superficial pattern of the impressions, and it is impossible to speak with absolute confidence as to their nature. The author of the species makes use of the generic name Equisetum; but in view of our ignorance of structural features it is better to adopt the more usual term Equisetites.
Since Kidston’s description was published I noticed a specimen in the British Museum collection which throws some further light on this doubtful fossil. Part of this specimen is shown in fig. 57, A. The stem is 21 cm. ”

“ Mrs. A. E. Bush, of San Jose, Cal., has sent me specimens of an Equisetum, collected at the hills near that city, April 22, which must be referred to the above species. The stalks are densely tufted, and the grooves of the stem vary from 5 to 10, but are commonly 6 or 7 ”

“ Perhaps the reader may ask why the Equisetum should be taken as the prototype of the file, and the skin of the Dog-fish{267} as that of sand-paper. The reason is this. The flinty points of the Equisetum are set upon parallel ridges something like those of a file, while the scales of the Dog-fish are without any apparent order, being crowded against each other like the cutting particles upon the sand-paper. That there should not be an order, and that a definite one, is out of the question. ”

“ On the germination of the spore the gametophyte is developed in the form of a small lobed prothallium 1–2 cm. in length. In most cases there are distinct male and female prothallia.
The genus Equisetum L., the common Horse-tail, is the sole living representative of this Family. It occurs as a common native plant in Britain, and has a wide geographical distribution. Species of Equisetum are abundant in the temperate zones of both hemispheres, and occur in arctic as well as tropical latitudes. ”

“ Minute as they are, these spicules can do their work, and they enable the joiner to finish off work in a manner that could not be accomplished by any tool made by human hands.
I find, by recent inquiries, that modern joiners scarcely, if ever, use the Equisetum, preferring emery-paper as cheaper and more expeditious, and knowing that the popular eye is not able to appreciate the difference of the surface obtained by{265} the Equisetum from that which is given by the finest emery-paper ever made. ”

“ There is little harm in retaining provisionally the two families already referred to, if we do not allow a purely arbitrary classification to prejudice our opinions as to the affinities of the several members of the Equisetales.
The Equisetaceae might be defined as a family including plants which were usually herbaceous but in some cases arborescent, bearing verticils of leaves in the form of sheaths more or less deeply divided into segments or teeth. The strobili were isosporous and consisted of a central axis bearing verticils of distally expanded sporophylls with sporangia, as in Equisetum. ”

“ It is wiser to admit that in many cases we are without the means of accurate diagnosis, and that the specific names applied to fossil Equisetums do not always possess much value as criteria of taxonomic differences.
The specimens of fossil Equisetums are usually readily recognised by the coherent leaf-segments in the form of nodal sheaths resembling those of recent species. The tissues of the cortex and central cylinder are occasionally represented by a thin layer 259of coal pressed on to the surface of a sandstone cast, or covering a flattened stem-impression on a piece of shale. ”

“ In others the fertile and barren shoots are alike green, and either both unbranched (E. hiemale) , or branched (E. palustre, E. limosum, etc) . The fertile shoots of E. silvaticum, up to maturity, resemble those without chylorophyll of E. arvense, but after that period they produce green branches, and thus resemble the barren ones.
Fig. 225.—Spores of Equisetum: A damp, with elaters (e) coiled round the spore; B dry, with elaters expanded.
Extinct isosporous Equisetinæ. ”

“ Moreover, in the case of fossil Equisetums we know nothing of their internal structure, and our comparisons are limited to external characters. Stems, cones, tubers, and leaves are often very well preserved as sandstone casts with distinct surface-markings, but we are still in want of petrified specimens. There is indeed evidence that some of the Triassic and Jurassic species of Equisetites, like the older Calamites, possessed the power of secondary growth in thickness, but our deductions are based solely on external characters. ”

“ The continuity of the cortical tissue is interrupted by the occurrence of large longitudinal vallecular canals alternating in position with the stem ridges and vascular strands (fig. 52, C, v) . The epidermis consists of a single layer of cells, containing stomata, and with the outer cell-walls impregnated with silica.
In certain species of Equisetum, e.g. E. palustre L., the whole circle of vascular strands is enclosed by an endodermis, and has the structure typical of a monostelic stem. In others e.g. ”

“ The prosenchymatous 327form of the principal medullary rays is seen in fig 83, C, and the reticulate pitting on the radial wall of a tracheid is shown in fig. 83, B. Fig. 83, A illustrates the large infranodal canals as seen in a tangential section of a stem. The same section shows also the course of the vascular bundles characteristic of Calamites as of Equisetum, and the position of outgoing leaf-traces is represented by unshaded areas in the black vascular strands. ”

“ The leaves, however, are not always grouped in the way in which they were described by M. Duchartre, [Pg 323] but more commonly form a single continuous line; when arranged in leaf-whorls it generally happens that some of the leaves are turned downwards, while others are erect. It has been said that this condition occurs particularly frequently in plants growing in damp places. It is certainly true that spiral torsion of the stem is specially frequent in the species of Equisetum, most of which grow in such spots. ”

“ Shropshire.
Fig. 362.
Calamites cannæformis, Schlot. (Foss. Flo. 79.) Lower end with rootlets.
Fig. 363.
Calamites Suckowii, Brong.; natural size. Common in coal throughout Europe.
Equisetaceæ.—To this family belong two species of the genus Equisetites, allied to the living "horse-tail" which now grows in marshy grounds. Other species, which have jointed stems, depart more widely from Equisetum, but are yet of analogous organization. [p.314] They differed from it principally in being furnished with a thin bark, which is represented in the stem of C. Suckowii (fig. 363.) ”

“ The stems are very narrow and the tubers have a characteristic elliptical form; the species is of little value botanically, but it affords another instance of the common occurrence of these tuberous branches in the Wealden Equisetums.
Similar fossil tubers, on a much larger scale, have been found in association with the Triassic Equisetites arenaceus; with E. Parlatori Heer [541] , a Tertiary species from Switzerland, and with other Mesozoic and Tertiary stems. E. Burejensis [542] , described by Heer from the Jurassic rocks of Siberia, bears a close resemblance to the Wealden species. ”

“ Philostratus tells us that the long-distance runner instead of training over the whole course would run eight or ten stades only, a practice quite in accord with that of the present day. [529] In those degenerate days athletes had also recourse to quack medicines and charms. A concoction of equisetum was recommended as a cure for the stitch, and some runners for a similar purpose wore a girdle of horses’ teeth. Athletes have always been superstitious. ”

“ In Woods and fallow Fields.
878. Equisetum palustre.—Bolt. Fil. t. 35.
In Ditches and by slow Streams.
879. Equisetum fluviatile.—Bolt. Fil. t. 36, 37.
In boggy Woods.
880. Equisetum limosum.—Bolt. Fil. t. 38. Eng. Bot. t. 929.
In Ponds and Mill Dams.
881. Equisetum hyemale.—Bolt. Fil. t. 39. Eng. Bot. t. 915.
In Woods.
882. Ophioglossum vulgatum.—Eng. Bot. t. 108. Bolt. Fil. t. 3. In Meadows near Gateshead.
883. Osmunda Lunarea.—Eng. Bot. t. 318. Bolt. Fil. t. 4.
On the Sea Coast between South Shields and Sunderland. On Lanchester Fell and near the High Force, Teesdale, D.
884. ”

“ Other Palaeozoic species of Equisetites have been recorded, but with one exception these need not be dealt with, as they do not add anything to our knowledge of botanical importance. The specimen described in the Flore de Commentry as Equisetites Monyi, by Renault and Zeiller [506] , differs from most of the other Palaeozoic species of Equisetites, in the fact that we have a stem with short internodes bearing a leaf-sheath at each node divided into comparatively long and distinct teeth. ”

“ The examples which have been selected may serve to illustrate the kind of specimens that are usually met with, as well as some of the possible sources of error which have to be borne in mind in the description of species.
Such Tertiary species as have been recorded need not be considered; they furnish us with no facts of particular interest from a morphological point of view. The wide distribution of Equisetites, especially during the Jurassic period, is one of the most interesting lessons to be learnt from a review of the fossil forms. ”

“ Cone or spike of fructification; c. Scale detached from cone; d. Spore with elastic filaments; e. Vertical section of stem; f. Transverse section showing hexagonal cells.
The vascular tissue of the Equisetaceæ (Fig. 309, e, f) shows them to be of a higher grade than the ferns. More recently discovered Horse-tails, of Brazil, grow to a gigantic size, but even these are comparatively small when compared with the Calamites, and other fossil Equisetaceæ of the coal measures and new red sandstone. They all require a calcareous flinty soil for growth. ”

“ The molar teeth are hypselodont, and the premolars, with the exception of the first, resemble the molars in their pattern. The orbit is completely surrounded by bone. The incisors are chisel-shaped, with a pit on the free surface. The canines are rudimentary if present. The radius and ulna are fused, as are the tibia and fibula. Although for the sake of uniformity a family, Equidae, is here separated from its allies, it is quite impossible owing to the full state of our knowledge of this group to draw a really hard-and-fast line between this family ”

“ The femur is more like that of the Paloeotheria than that of the horse, and has only a small depression above its outer condyle in the place of the great fossa which is so obvious in the Equidoe. The fibula is distinct, but very slender, and its distal end is ankylosed with the tibia. There are three toes on the hind foot having similar proportions to those on the fore foot. The principal metacarpal and metatarsal bones are flatter than they are in any of the Equidoe; and the metacarpal bones are longer than the metatarsals, as in the Paloeotheria. ”

“ Often he considered in his mind how best he might get speech with the dame. For his privy pleasure this amorous King went to chase in that country where the seneschal had his castle. The lady being in her own house, Equitan craved a lodging for the night. By this means when the hunt was done, he could speak with her, and show what was in his heart. Equitan found the lady as discreet as courteous. He looked closely upon her, for she was fair of face and person, and sweet of semblance and address. Love bound him captive to his car. The god loosed a shaft which entered deeply in his breast. ”

“ And the holy prophet Ezekiel teaches and describes with a full exposition how vigour is restored to the dry bones, the senses return, motion is added, and the sinews coming back, the joints of the human body grow strong; how the bones which were very dry are clothed with restored flesh, and the course of the veins and the flow of the blood is covered by the veil of the skin drawn over them. As we read, the reviving multitude of human bodies seems to spring up under the very words of the prophet, and one can see on the widespread plain the new seed shoot forth. ”

“ I suspect that the ilium is broken in the middle, and, as a consequence, that the distance from the posterior to the anterior ends of the visible parts of the bone (6⋅6 inch) is somewhat greater than it should be. Hence the acetabulum probably appears to be longer than it naturally is. The postacetabular process (c) , which should articulate with the ischium, is swollen and thick, but thins off, above and behind, into a thin vertical plate, the posterior curved margin of which is broad and turned in, like a narrow shelf. ”

“ The lower ramus is really more horizontal than the upper (which used to be called the horizontal ramus) , and runs backward and outward from the body to meet the ramus of the ischium and so form the subpubic arch.
The ischium (fig. 16) , like the ilium and pubis, has the fundamental form of a three-sided prismatic ischium. rod. One extremity (the upper) completes the acetabulum, whilst the lower forms the large V. prominence, or tuber ischii. The surfaces of the bone are internal or pelvic, antero-external, and postero- external. The pelvic and postero
the innominate bone. ”