quercifolia!

Ribes nigrum.

Sambucus nigra laciniata!

racemosa laciniata.

Dipsacus fullonum.

Scabiosa atropurpurea!

Symphoricarpus racemosus.

Helianthus sp.!

Lonicera Periclymenum quercifolia!

Syringa persica laciniata!

Syringa vulgaris!

Nerium Oleander!

Lamium purpureum.

alb.u.m!

Salvia officinalis.

Solanum Dulcamara!

Fraxinus excelsior crispa.

Veronica austriaca.

Polemonium caeruleum.

Juglans regia laciniata!

heterophylla.

filicifolia.

Anemiopsis californica.

Chenopodium Quinoa.

Ulmus americana incisa.

f.a.gus sylvatica heterophylla!

laciniata!

aspleniifolia!

incisa.

salicifolia!

Mercurialis perennis.

Urtica dioica.

Quercus Cerris laciniata!

p.u.b.escens filicina.

Betula populifolia laciniata.

alba dalecarlica.

Alnus incana laciniata!

glutinosa laciniata!

quercifolia.

oxyacanthifolia.

Corylus Avellana heterophylla!

laciniata!

urticifolia.

Carpinus Betulus incisa!

quercifolia.

heterophylla.

Castanea vesca heterophylla.

quercifolia.

incisa.

Populus alba acerifolia.

palmata.

quercifolia.

balsamifera.

Orchis sambucina.

Arum maculatum.

Filices sp. pl.

See also Schlechtendal, 'Bot. Zeit.,' tom. xiii, p. 823. A.

Braun, loc. supra citat. For Ferns too numerous for insertion, see Moore, 'Nature-Printed Ferns,' 8vo ed., 2 vols. Clos, 'Mem.

Acad. Toulouse,' 1862, p. 51.

=Fission of the petals, &c.=--The floral leaves are subject to a similar process of cleavage to that which has just been mentioned as taking place in the leaves. This, indeed, occurs very often as a normal occurrence as in the petals of mignonette (_Reseda_), or those of _Alsine media_ and many other plants. Here, however, we have only to allude to those instances in which the cleavage occurs in flowers whose sepals or petals are usually entire. Under this category Moquin mentions a petal of _Bra.s.sica oleracea_ completely split into two. Linne in his 'Flora Lapponica' (pp. 145 and 164) mentions quadrifid petals of _Lychnis dioica_, and much divided petals of _Rubus arcticus_. Among other plants subject to this division of sepals or petals may be mentioned as having come within the writer's personal observation, _Ranunculus Lingua_, _R. acris_, _Papaver somniferum_, and others of this genus, _Saponaria sp._, _Dianthus_, _Narcissus_, &c.

In some of the garden varieties of _Cyclamen_ the corolla looks at first sight as if double, and the plan of the flower is oblong or elliptical, instead of circular. In these flowers each lobe of the corolla is divided almost to the base into two lobes, so that there appear to be ten lobes to the corolla instead of five, as usual. The stamens are normal in form and number in these flowers.

In the paroquet tulips of gardeners the segments of the perianth are deeply and irregularly gashed, the segments occasionally becoming rolled up and their margins coherent so as to form little tubular spurs. I have also noticed the segments of the perianth in _Crocus_ and _Colchic.u.m_ deeply cleft, so much so sometimes, as to equal in this particular the stigmas. In the flowers of a species of _Oncidium_, communicated to me by Mr. Currey, the lip was divided into three segments perfectly distinct one from the other, but confluent with the column; the two side pieces had callosities at the upper edge close to the base, the central piece had a similar wartlike process in its centre. In these flowers the ovary, the stigma, and the anther were all in a rudimentary condition.

Some verbenas raised by Mr. Wills offer a curious ill.u.s.tration of this condition. It will be remembered that some of the lobes or petals of a verbena are normally divided at the base to a slight degree, but in the flowers in question this is carried to such an extent that the enlarged lobes are pushed into the centre of the flower and simulate, at a first glance, a distinct and separate organ, though in reality it is but an enlargement of what occurs normally.[74]

[Ill.u.s.tration: FIG. 29.--Flower of _Oncidium sp._ seen from the back.

The lip is divided into three unequal segments.]

Moquin mentions having seen the stamens of _Matthiola incana_ and _Silene conica_ completely divided, each section bearing half an anther, exactly as happens in _Polygalaceae_. In tulips and lilies the same author mentions division of the anther only, the filament remaining entire, as happens naturally in many species of _Vaccinium_.

A division of the individual carpels occurs very frequently when those organs become more or less leafy, as in _Trifolium repens_, and other plants to be hereafter mentioned.

The instances given in this chapter have all been cases wherein the division or the accessory growth has taken place in one plane only and that plane the same as that of the affected organ, but there are other examples, probably equally due to fissiparous division, where the new growth is either parallel to, or even at angle with the primary organ.

Of such nature are some of those instances wherein two leaves appear to be placed back to back. These partake of the nature of excrescences or of exaggerated developments, and hence will be more fully treated of under the head of hypertrophy. It must be remembered that in some of these cases the fission may be a resumption of characters proper to the species under natural conditions, but lost by cultivation or otherwise.

Thus, Mr. Buckman accounts for "finger-and-toe" in root-crops on the principle of reversion to the wild form.

FOOTNOTES:

[67] Loc. cit., p. 295.

[68] 'Bull. Soc. Bot. France,' 1857, p. 758.

[69] Masters, 'Jourl. Linn. Soc.,' vol. vii, p. 121.

[70] Cramer, 'Bildungsabweichungen,' p. 4, tab. vi, fig. 4, figures a case of the same kind in _Pinus Cembra_.

[71] 'Ann. des Science Nat.,' 2nd series, t. iv, p. 147, tab. v, figs. 3 and 4.

[72] 'Mem. Acad. Scien. Toulouse,' 5th series, vol. iii.

[73] Duchartre, 'Ann. Sc. Nat.,' 3rd series, 1848, vol. x, p. 207.

[74] Masters, 'Rep. Bot. Congress,' London, 1866, p. 136, tab. 7, f. 15, 16.