Introduction and Background

wn oO m a m m a THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA DAVIS Digitized by the Internet Archive in 2007 with funding from _ Microsoft Corporation http:/www.archive.org/details/introductiontoboO2lindrich ~, . e AN INTRODUCTION aa wl ; very She her?) te = O.T AN Y. BY JOHN LINDLEY, Pu. D. FBS, WITH SIX COPPER-PLATES AND NUMEROUS WOOD-ENGRAVINGS. FOURTH EDITION, WITH CORRECTIONS AND NUMEROUS ADDITIONS. IN TWO VOLUMES. VOL. I. LONDON: LONGMAN, BROWN, GREEN, AND LONGMANS, PATERNOSTER ROW. MDocexEVHT, -LIBRARY UNIVERSITY OF DAVIS CONTENTS OF VOL. IL. —— ORGANOGRAPHY (Continued.) Cuar. I, (Continued.) Pace Classifeation of Fruits 5. eG Germination Se 60, 62 Morphology of Floral Ogi el OO Cnar, III, Compound Organs in Flowerless = Ela or Asrogsns + 82 Ferns . 2 98 Lyeopodines - - 7 eet tt 98 Marsileaceso Sos oe ow = on ne JOE Mosses and Andrenceo «ss +s ss 106 a and Henelion 2 oe @ « 3 Me Lichens ee se one UY Fongsceo. - - ) ee tt DD BOOK II.—Puystotoey. Cuar. 1. General Considerations. 5 0. wee ts 18D Guin dL Vinlty 2 6. 0. ee eee ME Cuar, III. Chemical Constitution of the Elementary Organs...» (162 Guar. IV. ElementaryOrgns. 6 0.) se es Cuar, V. Root z . i . . . . F . . . 180 vi CONTENTS. Cuar. VI. Stem and the Origin of Wood Car. VIT. Leaves Caap. VII. Bracts Calyx and Corolla. Disengagement of Calorie . Cuar. IX. Fertilisation . Sexuality of Plants Mules nar, X, Fruit 2 Changes during ripening - Bletting : Cuar, XI. Seeds Germination ‘Action of Heat Their Longevity Cuap. XI, Food of Plants Carbon Water Nitrogen : Power of Selection Exhaustion of Soil Manures mar, XII, Digestion Docomptsition of Canbonite Add Cusr. XIV. Of Sceretions Cuar. XV. Of Respiration Cmar, XVI. Of the Movement of Fluids General Motion Rotation . Cyelosis BOOK III.—GxossoLoey. Absolute Terms 9... Division Surface Texture Size Duration Colour ‘ Venng ss Pagx 187 202 208 208 Qin 217 236 241 252 256 257 259 259 260 266 270 270 272 273 275 285 286 287 295 300 308 323 325 331 336 B44 358 363 366 367 368 369 373 CONTENTS. vii BOOK I11.—GtossoLocy (Continued.) maa Individual Relative Terms. rs a . « é . . . 874 Direction . . . . é 7 é - * a . . 876 Insertion . . . . . . * . * ¢ . . 878 Collective Terms . x « a . . . Fe . . . 380 Arrangement =. |) eee B80 Terms of Qualifeation =... ee BM Sigs. se BBE INTRODUCTION 10 BOTAN Y. BOOK I. ORGANOGRAPHY ; OR, OF THE STRUCTURE OF PLANTS. CHAPTER II. OF THE COMPOUND ORGANS IN FLOWERING PLANTS—continued, 14. Of the Fruit. The fruit (figs. 186. to 168.) is the ovary or pistil arrived at maturity. But, although this is the sense in which the term is strictly applied, yet in practice it is extended to what- ever is combined with the ovary when ripe. Thus the pine- apple fruit consists of a mass of bracts, calyxes, corollas, and ovaries; that of the nut, the acorn, and many others, of the superior dry calyx and ovary; that of the apple of a succulent superior calyx, corolla, and ovary; and that of the strawberry- blite ofa succulent inferior calyx and dry ovary. The fruit being the matured ovary, it should exhibit upon some part of its surface the traces of a style or stigma; and this mark will, in many cases, enable the student to distin- guish minute fruits from seeds. Many fruits were formerly called naked seeds, such as those of Umbellifers, Labiates, and Borageworts, and the grain of corn; but now that atten- tion has been paid to the gradual development of organs, such errors have been corrected. In cases where a trace of VOL. II. B 2 FRUIT. [Book 1. the style cannot be discovered, anatomy will generally show whether a minute body is a seed or fruit, by the presence, in the latter case, of two separable and obviously organically distinct coatings to the nucleus of the seed; but in other cases, where the pericarp and the integuments of the seeds are combined in a single covering, and where no trace of style remains, as sometimes happens, nothing can be deter- mined as to the exact nature of a given body without follow- ing it back in its growth to its young state. This, however, may be stated, that naked seeds, properly so called, are not known to exist, unless accidentally, in more than three or four orders in the whole vegetable kingdom; viz. in Conifers and Cycads, where the ovules also are naked, and in Peliosanthes Teta and Leontice, in which the ovules, originally enclosed in an ovary, uniformly rupture it at an early period after fertilisation, and subsequently continue naked until they become seeds. Such being the case, it follows that all the laws of structure which exist in the ovary are equally to be expected in the fruit; and this fact renders a repetition in this place of the general laws of formation unnecessary. Nevertheless, as, in the course of the advance of the ovary to maturity, many changes often occur which contribute to conceal the real structure of the fruit, it is in all cases advisable, and in many absolutely necessary, to examine the ovary, in order to be certain of the exact construction of the fruit itself. These changes are caused by the abortion, non-development, obli- teration, addition, or union of parts. Thus the three-celled six-ovuled ovary of the oak and the hazel becomes, by the non-development of two cells and five ovules, a fruit with one seed; the three-celled ovary of the cocoa-nut is converted into a one-celled fruit, by the obliteration of two cells and their ovules; and the two-celled ovary of some Pedaliads becomes many-celled, by a division and elongation of the pla- cent. In Cathartocarpus Fistula a one-celled ovary changes into a fruit having each of its many seeds lodged in a separate cell, in consequence of the formation of numerous horizontal membranes which intercept the seeds. A still more extra- ordinary confusion of parts takes place in the fruit of the STRUCTURE. ] PARTS OF THE FRUIT. 3 pomegranate after the ovary is fertilised; and many other cases might be mentioned. Every fruit consists of two principal parts, the pericarp and the seed, the latter being contained within the former. When the ovary is inferior, or coheres with the calyx, the latter and the pericarp are usually so completely united as to be inse- parable and undistinguishable: in such cases it is usual to speak of the pericarp without reference to the calyx, as if no such union had taken place. Botanists call a fruit, the peri- carp of which adheres to the calyx, an inferior fruit (fructus inferus); and that which does not adhere to the calyx, a superior fruit (fructus superus). But Desvaux has coined other words to express these ideas: a superior fruit he calls autocarpic ; an inferior fruit, heterocarpic ; terms unnecessary and unworthy of adoption. Everything which in a ripe fruit is on the outside of the real integuments of the seed, except the aril, belongs to the pericarp. It consists of three different parts, the epicarp, the sarcocarp, and the endocarp ; terms contrived by Richard, and useful in practice. The epicarp is the external integument or skin ; the endo- carp, called putamen by Gzrtner, the inner coat or shell ; and the sarcocarp, the intermediate flesh. Thus, in the peach, the separable skin is the epicarp, the pulpy flesh the sarco- carp, and the stone the endocarp or putamen. In the apple and pear the epicarp is formed by the cuticle of the calyx, and the’ sarcocarp is confluent with the remainder of the calyx in one fleshy body. The pericarp is extremely diversified in size and texture, varying from the dimension of a single line in length to the magnitude of two-feet in diameter ; and from the texture of a delicate membrane to the coarse fabric of wood itself, through various cartilaginous, coriaceous, bony, spongy, succulent, or fibrous gradations. The base of the pericarp is the part where it unites with the peduncle; its apex is where the style was: hence the organic-and apparent apices of the fruit are often very different, especially in such as have the style growing from B2 4 DEHISCENCE. [B00K 1. their sides, as in Rosacee and Chrysobalanacex, Labiatz and Boraginacez. When a fruit has arrived at maturity, its pericarp either continues perfectly closed, when it is indehiscent, as in the hazelnut ; or separates regularly round its axis, either wholly or partially, into several pieces: the separation is called dehis- cence, and such pieces valves ; and the axis from which the valves separate, in those cases where there is a distinct axis, is called the columella. When the dehiscence takes place through the dissepiments, it is said to be septicidal ; when through the back of the cells, it is called loculicidal; if along the inner edge of a simple fruit it is called sutwral; if the dissepiments are separated from the valves, the dehiscence is named septifragal. In septicidal dehiscence the dissepiments divide into two plates and form the sides of each valve, as in Rhododendron, Menziesia, &c. Formerly botanists said that in this sort of dehiscence the valves were alternate with the dissepiments, or that the valves had their margins turned inwards. This may be understood from fig. 169., which represents the fig. 169. v\e [NX Aye) é* relative position of parts in a transverse section of a fruit with septicidal dehiscence ; v being the valves, d the dissepi- ments, and a@ the axis. Fg. 170. aes a d d v * In loculicidal dehiscence the dissepiments form the middle of each valve, as in the lilac, or in the diagram 170., : STRUCTURE. ] ANOMALOUS DEHISCENCE. 5 where the letters have the same value as above. In this it was formerly said that the dissepiments were opposite the valves. In septifragal dehiscence the dissepiments adhere to the axis and separate from the valves, as in Convolvulus; or in the diagram 171., lettered as before. fg V7. 7 a Ay) In sutural dehiscence there are no dissepiments, the fruit being composed of only one carpel, as the Pea. Besides these regular forms of valvular dehiscence, there is avery anomalous mode which occurs in a very few plants, and is called circumscissile. This takes place by a transverse cir- cular separation, as in Anagallis ; in Jeffersonia it only takes place half round the fruit. In some cases, as in lomentaceous legumes, the transverse disarticulation may be supposed to have some relation to the pinnate leaves, whose modification, in those instanges, forms the carpel. In other cases the explanation is far less obvious, and must be at least very different. Perhaps the best account of transverse dehiscence is that of Mr. Hincks, as reported in the Annals of Natural History, vol. xvii. “Tn the fruit, as in the calyx, this author believes that horizontal disruption arises from the force of cohesion of the parts of the circle, the absence of any of the causes favourable to dehiscence along the midrib of the carpellary leaf, and the operation of some force pressing either from without or from within on one particular line encircling the fruit. In the circumscissile capsule of Anagallis, he states that the central free receptacle with the seeds upon it continuing to enlarge in both diameters after the envelope has ceased to grow, and having occupied from the first the entire cavity, it is 6 ANOMALOUS DEHISCENCE. {Boox 1. naturally to be expected, since the chief extension of the inte- rior parts is upwards (the natural direction of growth), while the enlargement of the seeds in the lower half tends to press back the parts of the lower hemisphere, that uniform and regular pressure will resolve a nearly spherical capsule into two equal hemispheres. This remark he applies to Centun- culus also, but confesses himself at a loss to give any reason why the opening of Trientalis, which depends on the same general causes, should be irregular. For the separation of the lid of the capsule in Hyoscyamus he accounts by the con- traction and rigidity of the throat of the calyx exercising a gradually increasing pressure around the upper part of the capsule, and thus causing its separation by the first of the general principles laid down. Lecythis, he thinks is to be explained by the third of his general principles. In illustra- tion he refers to a monstrosity of the common Tulip. In this monstrosity, the upper leaf, being unusually developed, cohered by its edges so firmly as to imprison the flower, and this constraint occurring at a period when the stalk was increasing in length, and previous to any considerable en- largement of the flower-bud, the force applied was chiefly vertical, and carried off the upper part of the leaf in the form of a calyptra, leaving the lower part in the shape of a cup, from the centre of which the stem appeared to rise. The separation of the lid of the capsule of Lecythis, Mr Hincks believes to be effected in an analogous manner; the septa which form the two or four cells into which the fruit is divided, meet in a thickened axis, and the outer part of the fruit becoming (partly from its natural texture, and partly from the adherence of the torus and calyx) hard, solid, and fully grown, while the axis continues slowly to extend, and thus to press upwards that portion of the capsule which rests upon it, causes that portion first to become slightly prominent, and finally by a strain upon the vessels of that particular part to fall off in the shape of a lid. In Couroupita the pres- sure is sufficient to mark the surface of the fruit with a promi- nence, but from the partitions giving way early, and from the abundant juices produced in the interior, there has not been sufficient pressure to occasion disruption. In all the species ‘STRUCTURE.] FALSE DEHISCENCE. 7 of Lecythis, the extent of the loose cover corresponds with the extent of the axis, and what remains of the latter continues attached to it. As regards Lomentaceous fruits in general, the author believes that the intervals between the seeds being sufficient to admit of the sides of the fruit cohering (which is promoted in particular instances by special causes), the swelling of the seeds afterwards stretches the parts over them in a degree which this coherence prevents from being equally distributed, drags the tissue forcibly from the junc- tures which are fixed points, and thus there being a strain in each direction from the middle line of the juncture the contraction of drying in the ripening of the fruit effects the separation.” Valvular dehiscence, which is by far the most common mode by which pericarps open, must not be confounded with either rupturing or solubility,—irregular and unusual con- trivances of nature for facilitating the dispersion of seeds. In valvular dehiscence the openings have a certain reference to the cells, as has been already shown; but neither rup- turing nor solubility bear any distinct relation to the cells. Rupturing consists in a spontancous contraction of @ portion of the pericarp, by which its texture is broken through, and holes formed, as in Antirrhinum and Cam- panula. Solubility arises from the presence of certain transverse contractions of a one-celled pericarp, through which it finally separates into several closed portions, as in Ornithopus. For the nature of the placenta and umbilical cord see the observations under ovary. Of these parts, which are mere modifications of each other, the former often acquires a spongy dilated substance, occasionally dividing the cells by spurious dissepiments, and often giving to the fruit an appearance much at variance with its true nature. In some seeds, as Euonymus europzus, it becomes exceed- ingly dilated around each seed, forming an additional envelope, ealled aril. The true character of this organ was unknown till it was settled by Richard: before his time the term was applied, not only in its truc sense to an enlargement of the 8 MODIFICATIONS OF FRUIT. [soox 1. placenta, but also to the endocarp of certain Cinchonads and Rueworts, to the seed-coat of Jasminum, of Orchids, and others, and even to the perianth of Carex. A very remarkable instance of the aril is to be found in the nutmeg, in which it forms the part called the mace surrounding the seed. Itis never developed until after the fertilisation of the ovule. It will be further and much more particularly treated of, when speaking of the seed. Having thus explained the structure of the pericarp, it is in the next place necessary to inquire into the nature of its modifications, which in systematic botany are of considerable importance. It is, on the one hand, very much to be regretted that the terms employed in this department of the science, which is that of Carpology, have been often used so vaguely as to have no exact meaning; while, on the other hand, they have been so exceedingly multiplied by various writers, that the language of carpology is a mere chaos. In practice but a small number of terms is actually employed ; but for collec- tions of fruits, or minute carpological arrangements, a large’ number is desirable ; and it cannot be doubted that, if it were not for the excessive inconvenience of overburdening the sci- ence with words, it would conduce to clearness of description if botanists would agree to make use of some precise and uniform nomenclature. What, for instance, can be more embarrassing than to find the term nut applied to the superior plurilocular pericarp of ‘Verbena, the gland of Corylus, and the achenia of Rosa and Borago: and that of berry to the fleshy envelope of Taxus, the polyspermous inferior fruit of Ribes, the succulent calyx of Blitum, and several other things? " So much discordance, indeed, exists in the application of terms expressive of the modifications of fruit, that it is quite indispensable to give the definitions of some of the most eminent writers upon the subject in their own