Word Finder - conifers

definition

A plant belonging to the order Coniferales; a cone-bearing seed plant with vascular tissue, usually a tree.

The conifers make the most effective screens.

Forest trees also suffer from their ravages, especially the conifers (Lophyrus pini).

In other cases the leaves last several years, as in conifers, and may sometimes be found on eleven-year-old shoots.

Straggling forests, mainly of conifers, characterize the high plateaus of central Utah.

It is one of the handsomest of conifers, forming an elongated cone of foliage, which in some gardens has already reached 70 or 80 ft.

North of this southern hardwood forest there were pine forests on the sandier land, mixed hardwoods and conifers on the loam and clay, and tamaracks and cedar in the swamps.

The estate is famous for its plantations and Dutch gardens, the pinetum containing the most representative collection of araucarias, deodars and other conifers in Europe.

Its lower flanks are clothed with forests of beech, conifers and oak.

The order Cedrelaceae (which is entirely distinct from the Conifers) includes, along with the mahoganies and other valuable timber-trees, the Jamaica and the Australian red cedars, Cedrela odorata, and C. Toona respectively.

The upper regions of Mt Elgon, Mt Debasien and Mt Agoro are clothed with forests of conifers - juniper and yew - and witch-hazels (Trichocladus).

About 857,000 acres, or 85% of the whole forest land, are planted with conifers; and about 143,000 acres, or 15%, with deciduous trees, among which beeches and birches are the commonest.

The Pacific coast Transition zone is noted for its forests of giant conifers, principally Douglas fir, Sitka spruce, Pacific cedar and Western hemlock, Here, too, mosses and ferns grow in profusion, and the sadal (Gaultheria shailon), thimble berry (Rubus nootkamus), salmon berry (Rubus spectabilis) and devils club, (Fatsia horr-ida) are characteristic shrubs.

The island has extensive forests of conifers with an undergrowth of ferns and flowering plants, and bears are numerous.

The seeds are sown in April, on rich ground, which should not be too highly manured; the young larches are planted out when two years old, or sometimes transferred to a nursery bed to attain a larger size; but, like all conifers, they succeed best when planted young; on the mountains, the seedlings are usually put into a mere slit made in the ground by a spade with a triangular blade, the place being first cleared of any heath, bracken, or tall herbage that might smother the young tree; the plants should be from 3 to 4 ft.

The larch is said not to succeed on arable land, especially where corn has been grown, but experience does not seem to support this view; that against the previous occupation of the ground by Scotch fir or Norway spruce is probably better founded, and, where timber is the object, it should not be planted with other conifers.

The wood is the hardest and strongest of all the American conifers; it is durable and adapted for construction work or household furniture.

Cordaites, a tall plant (20-30 ft.) with yucca-like leaves, was related to the cycads and conifers; the catkin-like inflorescence, which bore yew-like berries, is called Cardiocarpus.

In England the pine is largely employed as a " nurse " for oak trees, its conical growth when young admirably adapting it for this purpose; its dense foliage renders it valuable as a shelter tree for protecting land from the wind; it stands the sea gales better than most conifers, but will not flourish on the shore like some other species.

Elms, limes and poplars are common north of the Tagus, ilexes, araucarias, myrtles, magnolias and a great variety of conifers in all parts.

It was the English botanist Robert Brown who first recognized this important distinguishing feature in conifers and cycads in 1825; he established the gymnospermy of these seed-bearing classes as distinct from the angiospermy of the monocotyledons and dicotyledons.

The best known and by far the largest division of the Gymnosperms is that of the cone-bearing trees (pines, firs, cedars, larches, &c.), which play a prominent part in the vegetation of the present day, especially in the higher latitudes of the northern hemisphere; certain members of this class are of considerable antiquity, but the conifers as a whole are still vigorous and show but little sign of decadence.

The line of descent of recent cycads is comparatively clear in so far as they have undoubted affinity with Palaeozoic plants which combined cycadean and filicinean features; but opinion is much more divided as to the nature of the phylum from which the conifers are derived.

There is no doubt that the result of recent research and of work now in progress will be to modify considerably the grouping of the conifers.

The stems of cycads are often described as unbranched; it is true that in comparison with conifers, in which the numerous branches, Stem springing from the main stem, give a characteristic form to the tree, the tuberous or columnar stem of the Cyca daceae constitutes a striking distinguishing feature.

During the growth of the ovum nourishment is supplied from the contents of the cells immediately surrounding the egg-cell, as in the development of the ovum of Pinus and other conifers.

Short and reticulately-pitted tracheal cells, similar to tracheids, often occur in the circummedullary region of cycadean stems. In an old stem of Cycas, Encephalartos or Macrozamia the secondary wood consists of several rather unevenly concentric zones, while in some other genera it forms a continuous mass as in conifers and normal dicotyledons.

The discovery by the Japanese botanist 'Erase of the development of ciliated spermatozoids in the pollen-tube of Ginkgo, in place of the non-motile male cells of typical conifers, served as a cogent argument in favour of separating the genus from the Coniferales and placing it in a class of its own.

Surrounding the pitted wall of the ovum there is a definite layer of large cells, no doubt representing a tapetum, which, as in cycads and conifers, plays an important part in nourishing the growing egg-cell.

A pendulous or weeping habit is assumed by some conifers, e.g.

Conifers are not infrequently seen in which a lateral branch has bent sharply upwards to take the place of the injured main trunk.

The flat branchlets of Cupressus, Thuja (arbor vitae), Thujopsis dolabrata (Japanese arbor vitae) are characteristic of certain types of conifers; in some cases the horizontal extension of the branches induces a dorsiventral structure.

A new genus of conifers, Taiwania, has recently been described from the island of Formosa; it is said to agree in habit with the Japanese Cryptomeria, but the cones appear to have a structure which distinguishes them from those of any other genus.

Sequoia sempervirens (redwood), Thuja occidentalis, &c. The leaves of conifers are characterized by their small size, e.g.

The occurrence of long and short shoots is a characteristic feature of many conifers.

The variation in leaf-form and the tendency of leaves to arrange themselves in various ways on different branches of the same plant are features which it is important to bear in mind in the identification of fossil conifers.

The long linear leaves of some species of Podocarpus, in which the lamina is traversed by a single vein, recall the pinnae of Cycas; the branches of some Dacrydiums and other forms closely resemble those of lycopods; these superficial resemblances, both between different genera of conifers and between conifers and other plants, coupled with the usual occurrence of fossil coniferous twigs without cones attached to them, render the determination of extinct types a very unsatisfactory and frequently an impossible task.

In the conifers proper the female reproductive organs have the form of cones, which may be styled flowers or inflorescences according to different interpretations of their morphology.

Robert Brown was the first to give a clear description of the morphology of the Abietineous cone in which carpels bear naked ovules; he recognized gymnospermy as an important distinguishing feature in conifers as well as in cycads.

Cordaites is an extinct type which in certain respects resembles Ginkgo, cycads and the Araucarieae, but its agreement with true conifers is probably too remote to justify our attri buting much weight to the bearing of the morphology of its female flowers on the interpretation of that of the Coniferae.

The nucleus of the microspore divides and gives rise to a small cell within the large cell, a second small cell is then produced; this is the structure of the ripe pollen-grain in some conifers (Taxus, &c.).

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.

The roots of many conifers possess a narrow band of primary xylem-tracheids with a group of narrow spiral protoxylem-elements at each end (diarch).

Wide areas are often exclusively occupied by conifers, which give the landscape a sombre aspect, suggesting a comparison with the forest vegetation of the Coal period.

In the far East conifers are richly represented; among them occur Pinus densiflora,Cryptomeria japonica, Cephalotaxus, species of Abies, Larix, Thujopsis, Sciadopitys venticillata, Pseudolarix Kaempferi, &c. In the Himalaya occur Cedrus deodara, Taxus, species of Cupressus, Finns excelsa, Abies Webbiana, &c. The continent of Africa is singularly poor in conifers.

The greater part of Africa north of the equator is without any representatives of the conifers; Juniperus procera flourishes in Somaliland and on the mountains of Abyssinia; a species of Podocarpus occurs on the Cameroon mountains, and P. milanjiana is widely distributed in east tropical Africa.

Nearly 60% of the entire duchy is occupied by arable land, and about 26% by forests, mainly consisting of conifers.

Evergreen oaks, chestnuts and conifers are the prevailing trees.

The conifers are spreading naturally.

Specimens of true Cycads or Conifers are rare or doubtful until we come to the latest Palaeozoic rocks.

Now that the numerous specimens of wood formerly referred to Coniferae are known to have belonged to distinct orders, but few true Palaeozoic Conifers remain to be considered.