765 



SICYONIA. 



SILAUS. 



SICYONIA. 



SIDA, a genus of Plants belonging to the natural order Mah'acccf, 

 containing nearly 200 species, which are very extensively distributed 

 throughout the warm parts of the world, and abound in the peninsula 

 and plains of India. The name was originally applied by Theophrastus 

 to a plant growing in moist situations, which ia believed to have been 

 an Alth&a, also belonging to the family of Malvacece, and was adopted 

 by Liuuceus for this genus. 



Sida ia characterised by having a naked quinquifid calyx with 

 valvate segments. Corolla with 5 petals, which are obovate, with 

 the claws often united into a tube, and joined to the bottom of 

 the stamen tube. The stamens numerous, with their filaments con- 

 nected into a columnar tube at their base, and free at the apex, bear- 

 ing the reniform anthers. The styles are numerous, but more or less 

 united at the base. Capsule 5- or many-celled. Cocci single seeded ; 

 seeds suspended, roundish, and flattened. 



The species of this genus vary much in habit, as well as in the 

 structure of their fruit and seeds, but they resemble each other, as 

 indeed do all Malvaceous plants, in abounding in mucilage, and in 

 some of them having tough ligneous fibres, which are employed for 

 the purposes of cordage in different countries. From their mucilag- 

 ino.i.- nature several are employed as demulcents in India, such as 

 Sida Indica, ,S'. Asiatica, and S. populifolia, in the same way that the 

 Mallow and the Marsh-Mallow are in Europe. The leaves of >S'. carpi- 

 i native of Brazil and the Canary Islands) are chewed by the 

 Hi ;i/.ili (is, and applied with success to the stings of wasps and bees. 

 X rkoibboidca and rhonibifolia, abound in very delicate flax-like 

 fibres, which may be used for many of the same purposes as hemp 

 and flax ; but when the plants are grown for the sake of their fibres, 

 they ought to be sown thick, under which circumstances, like other 

 plants similarly sown, they grow tall and slender without branches. 

 So .S'. perifilocifolia, a native of the Malay Islands, which succeeds 

 well in India, may be cultivated for the same object, especially as 

 when cut near the earth it quickly shoots iuto long simple twigs 

 which abound in flax-like fibres. A species, .S'. tiiicefolia, is actually 

 cultivated for this purpose in China. Seeds of this species were 

 received at the Calcutta Botanic Garden under the name of King-ma 

 from Pekin, in the neighbourhood of which the plant was said to be 

 cultivated as a substitute for hemp and flax. At Rio Janeiro the 

 straight shoots of .S'. macrantha are employed as roeket-sticka. 



SIDERASTRyEA. [MADREPHYLLICEA.] 



SIDERITE. [QUARTZ.] 



SIDERI'TIS (from ffiSrjpos, iron), the name of a genus of Plants 

 belonging to the natural order Laimaccie. The species of this genus 

 are numerous, and are inhabitants of Europe and the northern parts 

 of Asia. Dioscorides mentions three species of Sidcritit, which were 

 celebrated for stanching blood and healing wounds. 



The genus consists of herbs and shrubs, with small yellowish 

 flowers arranged in whorls ; a tubular 5-cleft calyx ; a riugent corolla, 

 with upper lip 2-parted, the lower lip spreading, and deeply 3-cIeft ; 

 four didynamous stamens, the upper short, bearing 2-celled anthers, 

 the lower ones longer, and bearing irregular empty anthers; an in- 

 closed style, bifid at the top, with one of the stigmas shorter and 

 embracing the other. 



>'. Romano, Koman Iron-Wort, is an annual, clothed with soft rather 

 woolly hairs, with oblong-ovate leaves; a nearly glabrous calyx, with 

 long mucronate teeth, the upper tooth large and ovate, the lower teeth 

 lanceolate. This plant is a native of the Mediterranean. It was found 

 by Dr. Sibthorp in Greece and the isles of the Archipelago ; and Sir J. E. 

 Smith believes it to be identical with the Sideritia of Dioscorides. It 

 flowers from June to August, and attains a height of about six inches. 



SIDEROPORA. [MADBEPOK^A.] 



SIDEROSCHISOLITE. [!BOX.] 



SIDERO'XYLON (from o-tt-npos and fiiXoc), a genus of Plants be- 

 longing to the natural order Kapotacecc. The species of this genus 

 are natives of Africa, America, the East Indies, and Australia. They 

 are evergreen trees, with axillary and lateral fascicles of flowers. 

 They are remarkable for the hardness and weight of their wood, 

 which sinks in water, and the genus has hence derived the name of 

 Iron-Wood. The .S'. incime (Smooth Iron-Wood) is a native of the 

 Cape of Good Hope, and lias long been cultivated in the greenhouses of 

 Europe. None of the species however are at all remarkable for beauty. 



SIKBOLDIA. [AMPHIBIA.] 



SIENITE. A compound of quartz, felspar, and mica, being called 

 Granite, we find in many instances hornblende instead of mica, and 

 the rock is then called Sieuite, or Syenite (from Syene in Egypt, 

 where such a rock is wll known). If we imagine (what is of com- 

 mon occurrence) the diminution of the quartz, and the partial obscu- 

 ration of the crystalline structure, the rock becomes greenstone. If 

 in place of hornblende we find hypersthene or epidote, the rock may 

 be called Hypersthenic, or Epidotic Sieuite, as in the Val di Fassa and 

 Shetland. Definition fails in respect of Sienite, as it does in regard to 

 other rocks of igneous origin. 



Dr. M'Culloch ('Treatise on Rocks') ranks two rocks usually called 

 Sienite (one composed of quartz, felspar, and hornblende, and the 

 oth'-r of quartz, felspar, hornblende, and mica) as Granite. Mount 

 Surrfl in Leicestershire, the Malvern Hills, and Criffel in Galloway, 

 afford abundant and characteristic lieuites. 



SIGARE'TUS. [CHISMOBBANCHIATA.] 



SIGHT. [EYE.] 



SIGILLARIA, the name of an extinct genus of Plants. It is known 

 by possessing a conical stem deeply furrowed but not jointed; with 

 oblong discoid or nearly rounded cicatrices or scars, not arranged in 

 a distinctly spiral manner, with frequently three smaller vascular 

 cicatrices in the centre of the larger scars. This genus includes the 

 Rliylidolepis, Alveolaria, Syrivgodendron, Catenaria, and the Lepido- 

 dendron punctatum, and L. appendiculatum of various authors. The 

 largest specimens of these plants occur in the coal-formation and in 

 beds of the mountain-limestone series. 



A variety of opinions have been entertained by geological botanists 

 as to the affinities of these plants. Artis thinks them related to 

 Euphorbiacete ; Schlothein refers them to Palms, and Von Martius to 

 Cactacece. Brongniart at one time thought them a family sui generis, 

 but has since referred them, with Count Sternberg, to the family of 

 Arborescent Ferns. Lindley and Hutton think that " the weight of 

 evidence seems to incline in favour of both Sigillaria and Stigaiaria 

 having been Dicotyledonous Plants, and of the highest degree of 

 organisation, such as Cactacece or Eitphorbiacece, or even Asclepmdacece." 

 To these families they seem to approach, particularly iu their soft 

 texture, in their deeply channelled stems, and especially in their scars 

 being placed in perpendicular rows between the furrows. These 

 writers however add that " in the total absence of all knowledge of 

 the leaves and flowers of these ancient trees, we think it better to 

 place the genus among other species the affinity of which is alto- 

 gether doubtful." 



Brongniart, in his 'Histoire des Vdge'taux Fossiles,' enumerates 

 59 species of KgiUaria, and Lindley and Huttou, in the ' Fossil Flora, ' 

 have figured eight species found in Great Britain. [CoAL-PLANTS,] 



The circumstances under which Sigillariie occur in the strata asso- 

 ciated with coal are remarkable, and probably may be interpreted so 

 as to reveal some of the conditions which were necessary for the 

 production of the vegetable mass of coal. The first thing which strikes 

 us is the hitherto almost universal absence of leaves, top, roots, and 

 interior structure; we generally find large fragments, or perhaps 

 almost the whole of the stems, furrowed, and marked by the bases of 

 leaves, but iu other respects deficient, truncate at top, and abruptly 

 ending toward the bottom. If the plant lies in laminated shale above 

 a bed of coal, it is generally compressed flat, having the exterior con- 

 verted to coal, and the opposite sides nearly or quite iu contact, to 

 the exclusion of the central (perhaps cellular) portions. If in grit- 

 stone above a bed of coal, we find it more or less transverse to the 

 strata, as if in attitude of growth, its top broken off, its lower part 

 enlarged and tumid, and nearly touching the coal-bed, but apparently 

 rootless; the interior full of sandy lamina) or irregular accumulations 

 of sand, fragments of other plants, lumps of ironstone, &c. The tree 

 was certainly hollow when the sandstone was formed ; but whether 

 through decay of the internal cellular substance, or a general wasting 

 and consumption of vascular and cellular structure, as suggested by 

 Mr. Hawkshaw 'from observations of hollowed dicotyledonous trees in 

 South America, is still doubtful. Whether the leafless and apparently 

 rootless trees, which in other respects are in the attitude and have 

 the aspect of growth, did really grow where they appear, and have 

 lost their roots by absorption and conversion into the coaly mass 

 below, or were deposited by drifting with their roots more or less 

 deficient, is a question of great importance, on which some of the 

 excavations on the line of the Boltou railway, a few milea north of 

 Manchester, have thrown much light. Here, above a thin (6-iuch) 

 coal-bed, in ehaly strata much inclined, are seen several furrowed 

 stems of trees, also inclined so as to stand at right angles to the strati- 

 fication, most of them evidently rooted, by dichotomising root- 

 branches, in the clay over the coal. The extremities of the roots are 

 not seen ; perhaps they entered the vegetable mass which is now coal, 

 and wre carbonised with the other plants. The stems are furrowed, 

 but less regularly than is usual in Siyillaria, and marked less plainly 

 than is usual with the cicatrices of leaves. The 'bark,' as it is called, 

 is coal, showing vegetable structure ; the interior is sedimentary rock. 

 These plants are commonly imagined to be Sigillaria ; at all events 

 some of them are likely to prove so (those iu which the roots are 

 least obvious, and the base is tumid) ; others appear to us to be as 

 much allied to Lepidodendron. We have seen specimens, in different 

 coal-districts, certainly congeneric, and presenting the same inter- 

 mediate characters between Sigillaria and Lepidodendron, Around 

 the bases Mr. Bowman collected abundance of Lepidostroli, which are 

 uaually referred to Lepidodendron. 



Upon the whole, it is clear that here trees analogous to Siyillaria 

 and Lepidodendron remain in the place, attitude, and circumstances of 

 growth ; their roots entered a sort of vegetable magma, partly the 

 fallen accumulation of leaves and fruits of the forests; over this mass 

 and around these stems water left its sediments horizontally; these 

 horizontal strata have been upheaved, and the once vertical sterna 

 made to slope iu accordance with the movement. These interesting 

 trees have been carefully preserved in situ, by the care of Mr. Hawk- 

 shaw, and models have also been made of them. 



SILANE. [DRACONINA.] 



SI'LAUS, a genus of Plants belonging to the natural order Umlelli- 

 fera;, and the tribe ticsdinea. The calyx is obsolete; the petals 



