FOSSIL PLANTS. 



651 



and which have for their fruit a time scaly cone, 

 as pinus, abies, cunninghamia, araucaria, &c. 



The coniferce are I'ound in large ibrests, in the 

 north of Europe, and America, and are most 

 important as timber trees, for all purposes. 

 Some species, as dcmmara australis and pimts 

 lamberliana, are said to attain a height of 200 

 feet or more. Oil of turpentine, resin, and pitch 

 are obtained from pintis sj/lvcstris, abies pectin- 

 ata, and other species. Spruce-beer is made from 

 an extract of the branches of abies canadensis. 

 The bark of the larch is said to equal that of 

 the oak for tanning. Juniperus sabina is sti- 

 mulant and diuretic. The berries of juniperus 

 communis, which are also diuretic, are employed 

 in the manufacture of gin. The berries of the 

 yew are said to be poisonous, and its leaves are 

 dangerous to cattle. 



Cycade.e, Rich. The cycadese, which are 

 composed of only two genera, ci/cas and zamia, 

 are extra-European plants, having the habit of 

 palms. Their leaves, which are collected at the 

 top of the stipe, are pinnate and rolled up in the 

 form of a crosier previous to their development, 

 as in the ferns. The flowers are always dioeci- 

 ous. The male flowers form catkins or cones, 

 which are sometimes very large, and which are 

 composed of spathulate scales, covered at their 

 lower surface by very numerous stamina, which 

 must be considered as so many male flowers. 

 The inflorescence of the female flowers is difl^er- 

 tnt in the two genera c!/cas and zamia. In the 

 former, a long, acute, spathulate spadix, toothed 

 cm the edges, bears at each tooth a female flower, 

 immersed in a small cavity. Zamia has its 

 female flowers also in a cone, and its scales, 

 which are thick and peltate, bear each at their 

 lower surface two reversed female flowers. 

 These flowers are composed of a globular calyx, 

 perforated by a very small aperture at its sum- 

 mit, and applied upon the ovary, ■which is in 

 part adherent at its base. The ovary is unilo- 

 cular and contains a single ovule ; it is termina- 

 ted at its summit by a nipple-like stigma. The 

 fruit is a kind of nut formed by the calyx, •which 

 sometimes is slightly fleshy. The pericarp is 

 generally thin, crustaceous and indehiscent, 

 and adheres to the proper integument of the 

 seed. The kernel is comjiosed of a fleshy endo- 

 spenn, containing an embryo with two unequal 

 cotyledons, sometimes adhering together, and 

 with the radicle united to the endospemi. 



However superficially one may compare the 

 structure of the male flowers, and cs])ecially of 

 the female flowers, of the cycadese with that of 

 the conifers, he will be struck with the very 

 great similarity that exists between the two 

 families, and cannot fail to adopt the opinion of 

 the elder Ilichard, who jilaces them beside each 

 other. In fact, in both, the male flowers con- 

 nist each of a mono-.iiermous perianth, and a 



semi-inferior ovary, with a single cell and a 

 single ovule. The fruit and the seed have the 

 same organization. It is ti-ue that the habit or 

 general aspect is entirely different in the two 

 lamilies, the cycadea; resembling the palms, and 

 the internal structure of the stem being that of 

 the monocotyledons. But this character ought 

 not to be sacrificed to the important resemblan- 

 ces w hich exist in the organization ot tlie flowers 

 of the cycadesE and coniieroe, whereby their 

 true place is evidently beside each other. 



A kind of sago is prepared from tiie central 

 parenchyma of cycas circinalis. 



CHAP. LVI. 



FOSSIL PLANTS. 



The history of those plants found imbedded in 

 the earth's strata, and which formerly flourished 

 on its surface, forms an interesting link in the 

 chain of vegetable being. Unfortunately, from 

 the mode in which the remains of these vegeta- 

 ble productions have been preserved, it in most 

 cases happens that only conjectures can be formed 

 regarding their peculiar characters. Most com- 

 monly, only pieces of the trunks and branches, 

 or fragments of the bark, or the leaves and 

 fruits, or pieces of the stems and roots, and rarely 

 or never the delicate inflorescence being pre- 

 served for our inspection. Yet, from these frag- 

 ments, it is wonderful how much has already 

 been ascertained of the form, and even minute 

 sti'ucture of many of those ornaments of a for- 

 mer state of things on the earth's surface. 



The number of fossil plants as yet known does 

 not much exceed five hundred. Like the cor- 

 responding fossil animals, these plants generally 

 are found to belong to existing classes and fami- 

 lies of plants, yet the species and even genera 

 are specifically different ; while in not a few 

 cases, totally new orders and genera have been 

 discovered, serving, from their structure, to fill 

 up blanks and chasms in the chain of existing 

 vegetable forms. Of this description are the Lc~ 

 pidodendrons, Sligmarice, Sigillariip, and others. 

 Vegetable remains, like animal, begin to make 

 their appearance in the lower beds of the secon- 

 dary series of locks, and as these rocks have 

 decidedly been accumulated and formed in the 

 bed of the ocean, we accordingly find that maiine 

 fuci are more or less plentifully scattered among 

 their successive layers; while in other situations 

 of the same strata, where the original deposit 

 has been formed by rivers or lakes, land plants 

 are accumulated in abundance. One gi-eat and 

 important deposit of ancient vegetation has 

 fonned the various coal-fields found in diffierenl 

 parts of the world ; and it is important to remark. 



