Codiaeum variegatum var.!

Spinacia oleracea.

Corylus avellana!

Polygonatum multiflorum.

Xanthosoma appendiculatum!

2. Calyptriform or hood-like pitchers, formed by the complete union of the margins, and falling off by a transverse fissure (as in the calyx of Escholtzia).

Tulipa Gesneriana.

B. _Polyphyllous._

1. Diphyllous, formed by the union of two leaves into a single cup, tube, or funnel, &c.

Pisum sativum (stipules)!

Cra.s.sula arborescens.

Polygonatum multiflorum.

2. Triphyllous, formed by the union of three leaves.

Paris quadrifolia var.

Besides the above varieties of ascidia formed from the union of one or more leaves, there are others which seem to be the result of a peculiar excrescence or hypertrophy of the leaf.

Such are some of the curious pitcher-like structures met with occasionally in the leaves of cabbages, lettuces, Aristolochia, &c. See Hypertrophy, cup-like deformities, &c.

In addition to other publications previously mentioned, reference may be made to the following treatises on the subject of ascidia:--Bonnet, 'Rech. Us. Feuilles,' p. 216, tab. xxvi, f. 1, _Bra.s.sica_; De Candolle, 'Trans. Hort. Soc.,' t. v, pl.

1, _Bra.s.sica_; Id., 'Org. Veget.,' I, 316; 'Bull. Soc. Bot.

Fr.,' I, p. 62, _Polygonatum_; 'Bull. Acad. Belg.,' 1851, p.

591, _Rosa_; Hoffmann, 'Tijdschrift v. Natuur. Geschied.,' vol.

viii, p. 318, tab. 9, _Ceratonia_; C. Mulder, 'Tijdschrift, &c.,' vol. vi, p. 106, tab. 5, 6, _Trifolium_, _Mimosa_, _Staphylea_;' Molkenboer,' p. 115, t. 4, _Bra.s.sica_.

FOOTNOTES:

[10] See a curious instance of this kind in the branches of _Pinus_.

'Regel. Garten Flora,' vol. 8, tab. 268.

[11] 'Bull. Soc. Bot. France,' 1860, p. 881.

[12] Ibid., 1861, p. 708.

[13] Ibid., 1860, p. 923.

[14] 'Proc. Linn. Soc.,' April 5, 1853.

[15] 'Organ. Veget.,' pl. iii, fig. 1.

[16] 'Bull. Acad. Roy. Bruxelles,' t. xviii, p. i and p. 591.

[17] 'Linnaea,' tom. 13, p. 383.

[18] 'Verhandl. Nat. Hist. Vereins,' 1859, Bonn, tom. xvi, tab. 3.

[19] 'Bull. Soc. Bot. Fr.,' vol. i, p. 62.

[20] 'Report of Internat. Bot. Congress,' London, 1866, p. 131, tab.

vii, figs. 10-13.

[21] 'Bull. Acad. Roy. Belg.,' t. xviii, 2nd part, p. 179.

[22] D. C., 'Organ. Veget.,' pl. xvii, fig. 3, and pl. xlviii, fig. 2.

[23] 'Mem. Acad. Toulouse,' 1862.

[24] Bonnet, 'Recherches Us. feuill.,' pl. xxi, fig. 2.

[25] De Candolle, 'Mem. Leg.,' pl. v, fig. 14.

[26] 'Phil. Bot.,' -- 125.

[27] 'Nov. Act. Acad. Nat. Cur.,' 14, p. 642, t. x.x.xvii.

[28] 'Journal of the Linn. Soc. Bot.,' vol. iv, p. 55.

[29] 'Bull. Acad. Roy. Bruxelles,' 1838, t. v, p. 582. 'Bull. Acad. Roy.

Belg.,' 1852, t. xix, part iii, p. 437.

CHAPTER II.

ADHESION.

Adhesion, so called, occurs either from actual union of originally distinct members of different whorls or from the non-occurrence of that separation which usually takes place between them. It is thus in some degree a graver deviation than cohesion, and is generally a consequence of, or at least is coexistent with, more serious changes; thus if two leaves of the same whorl are coherent the change is not very great, but if two leaves belonging to different whorls, or two leaves in the same spiral cycle are adherent, a deformation in the axis or a certain amount of dislocation must almost necessarily exist. Adhesion as a normal occurrence is usually the result of a lack of separation rather than of union of parts primitively separate. Instances of adhesion between different organs is seen under ordinary circ.u.mstances in the bract of the Lime tree, which adheres to the peduncle, also in _Neuropeltis_, while in _Erythrochiton hypophyllanthus_ the cymose peduncles are adherent to the under surface of the leaf.

Adhesion between the axes of the same plant is sufficiently treated of under the head of Cohesion, from which it is in this instance impossible to make a distinction. Adhesion of the inflorescence is necessarily a frequent accompaniment of fasciation and cohesion of the branches.

=Adhesion of foliar organs= may occur either between the margins or between the surfaces of the affected parts; in the former case there is almost necessarily more or less displacement and change of direction, such as a twisting of the stem and a vertical rather than a horizontal attachment of the foliar organ to it; hence it generally forms but a part of other and more important deviations.

=Adhesion of leaves by their surfaces.=--The union of leaves by their surfaces is not of very frequent occurrence, many of the instances cited being truly referable to other conditions. Bonnet describes the union of two lettuce leaves, and Turpin that of two leaves of _Agave americana_, in which latter the upper surface of one leaf was adherent to the lower surface of the leaf next above it, and I have myself met with similar instances in the wallflower and in lettuce and cabbage leaves; other instances have been mentioned in _Saxifraga_, _Gesnera_, _&c._[30]

In these cases, owing to the non-development of the internodes, the nascent leaves are closely packed, and the conditions for adhesion are favorable, but in most of the so-called cases of adhesion of leaf to leaf by the surface, a preferable explanation is afforded either by an exuberant development (hypertrophy) or by chorisis (see sections on those subjects). Thus, when a leaf of this kind is apparently so united, that the lower surface of one is adherent to the corresponding surface of another, the phenomenon is probably due rather to extra development or to fission. There is an exception to this, however, in the case of two vertically-erect leaves on opposite sides of the stem; here the two upper or inner surfaces may become adherent, as in an orange, where two leaves were thus united, the terminal bud between them being suppressed or abortive.

Adhesion between the membranous bract of _Narcissus poeticus_ and the upper surface of the leaf is described by Moquin.[31] The same author mentions having seen a remarkable example of adhesion in the involucels of _Caucalis leptophylla_, the bracts of which were soldered to the outer surface of the flowers. M. Bureau[32] mentions an instance wherein the spathe of _Narcissus biflorus_ was partially twisted in such a manner that the lower surface of its median nerve was adherent to the corresponding surface of one of the sepals, mid-rib to mid-rib, thus apparently confirming a law of G. de Hilaire, that when two parts of the same individual unite, they generally do so by the corresponding surfaces or edges, but the rule is probably not so general in its application as has been supposed.

=Adhesion of foliar to axile organs.=--The appendicular organs may likewise be found united to the axile ones. This union takes place in many ways; sometimes the leaves do not become detached from the stem for a considerable distance, as in the so-called decurrent leaves, at other times the leaves are prolonged at their base into lobes, which are directed along the stem, and are united with it. Turpin records a tendril of a vine which was fused with the stem for some distance, and bore leaves and other tendrils. Union of the leaf or bract with the flower-stalk is not uncommon. It occurs normally in the Lime and other plants.

=Adhesion of the sepals to the petals= is spoken of by Morren as calyphyomy, [Greek: kalyx phyomai.][33] Moquin cites an instance in _Geranium nodosum_, in which one petal was united by its lower surface to one of the segments of the calyx. A similar circ.u.mstance has been observed in _Petunia violacea_ by Morren. Duchartre describes an instance wherein one of the outer sepals of _Cattleya Forbesii_ was adherent to the labellum.[34]