. Fossil plants : for students of botany and geology . Paleobotany. 162 CONIFEBALES (RECENT) [CH. Sources of error in the detertnincUion of fossil Conifers. The determination of fossil Conifers is one of the most difficult tasks of the palaeobotanist. It is comparatively seldom that well- preserved cones are found in organic connexion with the twigs that bore them and the cones rarely exhibit those features which are the best guides to affinity. Excessive trust in superficial similarity has frequently led to the em- ployment of generic names suggesting relationships which are thoroughly mis- l
. Fossil plants : for students of botany and geology . Paleobotany. 162 CONIFEBALES (RECENT) [CH. Sources of error in the detertnincUion of fossil Conifers. The determination of fossil Conifers is one of the most difficult tasks of the palaeobotanist. It is comparatively seldom that well- preserved cones are found in organic connexion with the twigs that bore them and the cones rarely exhibit those features which are the best guides to affinity. Excessive trust in superficial similarity has frequently led to the em- ployment of generic names suggesting relationships which are thoroughly mis- leading. In comparing fossil and recent forms authors are apt to confine their attention to the better-known types, forgetting that it is often with the less familiar and geographically restricted genera that extinct plants are most closely allied. Even the data supplied by petrified wood are often insufficient to enable the student to do more than refer a specimen to some comprehen- sive genus based on characters shared by several recent genera. Though it is as a rule easy to distinguish between the wood of a Conifer and that of Cycads and Dicotyledons, the agree- ment between the xylem elements of many Cycads and those of the Arau- carineae is sufficiently close to afford opportunity for error. The homo- geneous structure of the secondary wood of some Magnoliaceous genera, , Trochodendron and Dritnys^ (fig. 710), closely simulates that of a Conifer, but the medullary rays are approxi- mately equal in breadth to the tra- cheids and the cells are more elongated ^ Groppler (94); Solereder (99) p. 34; (08) p. 5. See also JefErey and Cole (16).. Fir„710. Drimys Winteri. Trans- verse section of part of a stem. p, pith; /, pericycle fibres; c. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Seward,
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishercambr, bookyear1898
