The two species of Sequoia, the Wellingtonia (S.
Peculiar to California are the two species of sequoia (q.v.), - the redwood (S.
The Coast Range is heavily forested in the north, where rainfall is abundant in all seasons; but its lower ranges and valleys have a scanty tree growth in the south, where the rainfall is very light: here grow redwoods (Sequoia semperzirens) and live oaks (Quercus agrifolia).
Sequoia sempervirens (redwood), Thuja occidentalis, &c. The leaves of conifers are characterized by their small size, e.g.
Sequoia sempervirens, the fertile branches bear leaves which are less spreading than those on the vegetative shoots.
It has been shown by Lawson that in Sequoia sempervirens (Annals of Botany, 1904) and by other workers in the genera that several megaspores may attain a fairly large size in one prothallus.
In the genus Sequoia there may be as many as sixty archegonia (Arnoldi and Lawson) in one megaspore; these occur either separately or in some parts of the prothallus they may form groups as in the Cupressineae; they are scattered through the prothallus instead of being confined to the apical region as in the majority of conifers.
It has been suggested that transfusion-tracheids represent, in part at least, the centripetal xylem, which forms a distinctive feature of cycadean leaf-bundles; these short tracheids form conspicuous groups laterally attached to the veins in Cunninghamia, abundantly represented in a similar position in the leaves of Sequoia, and scattered through the so-called pericycle in Pinus, Picea, &c. It is of interest to note the occurrence of precisely similar elements in the mesophyll of Lepidodendron leaves.
The two surviving species of Sequoia afford an illustration of the persistence of an old type, but unfortunately most of the Mesozoic species referred to this genus do not possess sufficiently perfect cones to confirm their identification as examples of Sequoia.
P. Penhallow of Montreal has described the anatomical structure of the stem of Sequoia Langsdorfii, a Tertiary species occurring in Europe and North America.
Among modern floras we find here and there isolated types, such as Ginkgo, Sequoia, Matonia, Dipteris and the Cycads, persisting as more successful survivals which have held their own through the course of ages; these plants remain as vestiges from a remote past, and as links connecting the vegetation of to-day with that of the Mesozoic era.
Callitris (2 species), Sequoia, Athrotaxis (?) Ginkgo, Podocarpus, Pinus; and several genera of palms, of which the tropical Nipa is the most abundant and most characteristic, among the others being fan-palms of the genera Sabal and Chamaerops.
Several species of Nyssa are common to the two districts, as are a climbing palm, two vines, a magnolia, &c. The common tree at Bovey is Sequoia Couttsiae, which probably grew in profusion in the sheltered valleys of Dartmoor, close to the lake.
Among the types of vegetation which make their appearance in Europe during the Oligocene period may be mentioned the Conifers Libocedrus salicornioides, several species of Chamaecyparis and Sequoia, Taxodium distichum and Glyptostrobus europaeus.
The plants of Disco include, besides the plane and Sequoia, such warm-temperate trees as Ginkgo, oak, beech, poplar, maple, walnut, lime and magnolia.
Sequoia (which had already appeared in the American Upper Cretaceous) and the deciduous cypress (Taxodium distichum) are found in Europe.
70 contained Sequoia, planes, maples and magnolias, and closely agrees with the Miocene flora of central Europe.
Sequoia and the tulip-tree still remain; figs are abundant; laurels are represented by Sassafras and camphor; herbaceous plants (Ranunculaceae, Cruciferae, Umbelliferae) are present, though, as might be expected, only fragmentarily preserved.
SEQUOIA, a genus of conifers, allied to Taxodium and Cryptomeria, forming one of several surviving links between the firs and the cypresses.
At the much Sequoia sempervirens - a, Branch with green cones and male catkins; b, Section or cone; c, Scale of cone.
The western slope of the Sierra Nevada hears fine forests similar to those of the Cascade Range and of the Coast Range, but of more open growth, and with the redwood exchanged for groves of big trees (Sequoia gigantea) of which the tallest examples reach 325 ft.
The mammoth redwood tree of California,Sequoia (Wellingtonia) gigantea, which represents the tallest Gymnosperm, is a good example of the regular tapering main stem and narrow pyramidal form.
Smaller cones, less than an inch long, occur in the larch, Athrotaxis (Tasmania), Fitsroya (Patagonia and Tasmania), &c. In the Taxodieae and Araucarieae the cones are similar in appearance to those of the Abietineae, but they differ in the fact that the scales appear to be single, even in the young condition; each cone-scale in a genus of the Taxodiinae (Sequoia, &c.) bears several seeds, while in the Araucariinae (Araucaria and Agathis) each scale has one seed.
Sequoia) the primary tetrarch structure is easily identified in the centre of an old root, but in other cases the primary elements are very difficult to recognize.
Nageia) a canal occurs below each vein; in Tsuga, Torreya, Cephalotaxus, Sequoia, &c., a single canal occurs below the midrib; in Larix, Abies, &c., two canals run through the leaf parallel to the margins.
In the Mediterranean region occur Cupressus sempervirens, Pinus Pinea (stone pine), species of juniper, Cedrus atlantica, C. Libani, Callitris quadrivalvis, Pinus montana, &c. Several conifers of economic importance are abundant on the Atlantic side of North America - Juniperus virginiana (red cedar, used in the manufacture of lead pencils, and extending as far south as Florida), Taxodium distichum (swamp cypress), Pinus rigida (pitch pine), P. mitis (yellow pine), P. taeda,P. palustris, &c. On the west side of the American continent conifers play a still more striking role; among them are Chamaecyparis nutkaensis, Picea sitchensis, Libocedrus decurrens, Pseudotsuga Douglasii (Douglas fir), Sequoia sempervirens, S.
Soc. (1906) (with bibliography); Lawson, " Sequoia sempervirens," Annals of Botany (1904); Robertson, " Torreya Californica," New Phytologist (1904); Coker, " Gametophyte and Embryo of Taxodium," Bot.
The Genus Sequoia," Mem.
Some of the best examples of cones and twigs referred to Sequoia are those described by Heer from Cretaceous rocks of Greenland, and Professor D.
Forty-six species occur, namely, 32 species of pitch trees (18 pines), 12 species of the cypresses and their allies (2 sequoia), and 2 species of yews or their allies.
15, D) Sequoia, &c., there are always two sets of bundles; the upper set, having the phloem uppermost, as in the seminiferous scale of Abies or Pinus, are regarded as belonging to the outgrowth from the carpellary scale and specially developed to supply the ovules.