FOOTNOTES:
[376] Braun, 'Pringsheim Jahrbuch f. Wiss. Bot.,' 1858, 1, p. 307, tab. 22, 23.
[377] Henfrey, 'Jour. Linn. Soc. Bot.,' vol. iii, p. 159.
[378] On the subject of chorisis or dédoublement the reader may profitably consult Moquin-Tandon, 'Ess. sur les Dédoublements,' and the same author in 'Ann. Sc. Nat.,' t. xxvii, p. 236. and 'El. Ter. Veget.,' p. 337. Dunal, 'Consid. Org. Fleur.,' Montpell., 1829, p. 32, note 3. A. de St. Hilaire in 'Ann. Sc. Nat.,' ser. 3, t. iii, p. 355, adnot. Lindley, 'Elements of Botany,' p. 76. Asa Gray. 'Botanical Text Book.'
CHAPTER I.
MULTIPLICATION OF AXILE ORGANS, INFLORESCENCE, ETC.
By Linné an undue number of branches was designated as "plica," from the analogy with the disease of the hair known as plica polonica: "Plicata dicitur planta, cum arbor vel ramus excrescit minimis intertextis ramulis, tanquam plica polonica ex pilis, ceu instar nidi Picæ, quod vulgo a genio ortum arbitratur; frequens apud nos in Betula, præsertim Norlandiæ, in Carpino Scaniæ, nec infrequens in Pinu."[379]
By some of the older authors this condition was called polyclady. In some cases, it would seem to be due to fungi as in the witches' brooms (hexenbesen) of the German forests; in other instances, it is a result of mutilation as after the operation of pollarding.
Moquin-Tandon[380] mentions a case in a grafted ash in the botanic garden of Toulouse, where below the graft there was a large swelling, from which proceeded more than a thousand densely-packed, interlacing branches.
This must have been similar to the condition so commonly met with in the birch, and frequently in the hornbeam and the thorn, and which has prompted so many a schoolboy to climb the tree in quest of the apparent nest. It is probable that some of the large "gnaurs" or "burrs," met with in elms, &c., also in certain varieties of apples, are clusters of adventitious buds, some of which might, and sometimes do, lengthen out into branches.
An increased number of branches also necessarily arises when the flower-buds are replaced by leaf-buds.
Fig. 179.—Flower stalks of Bellevalia comosa, nat. size, after Morren.
Occasionally, a great increase in the number of pedicels, or flower-stalks, may be met with in conjunction with a decreased number of flowers, as in the wig-plant (Rhus Cotinus), or the feather-hyacinth (Bellevalia comosa). In these cases the supernumerary pedicels are often brightly coloured. To this condition Morren gave the name mischomany, from μἱσχος, a pedicel, a term which has not generally been adopted.[381]
Fig. 180.—Tuft of branches at the end of the inflorescence of Bellevalia comosa, enlarged after Morren.
M. Fournier[382] describes a case in the butcher's broom (Ruscus aculeatus), wherein from the axil of the minute leaf subtending the flower a secondary flattened branch proceeded.
Duchartre[383] cites the case of a hyacinth which, in addition to the usual scape, had a second smaller one by its side terminated by a solitary flower; indeed, such an occurrence is not uncommon.
Some tulips occasionally present three or four, or more, flowers on one inflorescence, but whether from a branching of the primary scape, or from the premature development of some of the axillary bulbils into flowering stems which become adherent to the primary flower-stalk, cannot, in all cases, be determined. Certainly, in some cases examined by me the latter was the case.[384]
Under this head, too, may be included those cases wherein an ordinarily spicate inflorescence becomes paniculate owing to the branching of the axis and the formation of an unwonted number of secondary buds. Instances of this kind may be met with in willows, hazels, alders, and other amentaceous plants. In the case of the hazel the unusual development of male catkins sometimes coincides with an alteration in their position, instead of being placed near the axil of a leaf; they become terminal. Jaeger figures and describes a bunch of Pinus sylvestris bearing in one case seventy minute cones, and in another fifty-nine. These cones preserved the same spiral arrangement among themselves which is proper to the leaves. These latter, indeed, replaced the strobili above.[385]
Fig. 181.—Increased number of male catkins in the hazel Corylus avellana.
M. Reichardt describes an analogous case in the same species, and attributes the inordinate number of cones to a fungus (Peridermium pini). In this case there were no less than 227 cones, but each one half the size of the ordinary cones.[386]
Of a similar character is the many-headed pineapple. Among grasses such a branching of the inflorescence is exceedingly common,—which is the more readily understood as the normal inflorescence is in so many cases paniculate. Cultivators have, in some instances, availed themselves of this peculiarity, as in the Egyptian wheat or corn of abundance (Triticum compositum), certain varieties of Maize, etc. Similar exuberant growths occur in Orchidaceæ, in Cyperaceæ, e.g. Carex, in Restiaceæ, and indeed they may be found in any plant with a similar form of inflorescence. In all these cases the branching begins at the lower part of the spike, and extends from below upwards in an indefinite manner, even although the primary inflorescence be definite.
Among the Equisetaceæ a similar plurality of spikes occurs often as a result of mutilation.[387] The deviation in question might in some instances be turned to good account, as in the Triticum before mentioned or as in the broccoli shown at fig. 182, though it must be added that the apparent advantages are often counterpoised by some undesirable qualities or by some circumstance which prevents us availing ourselves of the new condition.
Multiplication of Bulbs.—This occurrence has been briefly alluded to previously ([see p. 84]). The most curious cases are those in which one bulb is placed on the top of another as happened in some bulbs of Leucoium æstivum described by M. Gay.[388] Irmisch described a similar phenomenon in L. vernum; and Mr. Moggridge has communicated drawings of a similar formation in the same species grown in the neighbourhood of Mentone.
From the instances cited it is clear that branching of the inflorescence occurs most frequently in those plants naturally characterised by a dense compact mode of growth, whether that be definite or indefinite, as in spikes, umbels, capitula, &c.; so that compound spikes, umbels, &c., are formed in the place of simple ones (see also prolification of the inflorescence, [p. 102]).
Fig. 182.—Broccoli, with six perfect heads on one stalk ('Gard. Chron.,' 1856, Oct. 25).
Increased number of florets in the individual spikelets of grasses is also met with under some circumstances. I have seen this in Hordeum and Lolium, and an instance is figured in Avena by Dr. Wiegmann.[389] M. Duval Jouve[390] records a similar occurrence in Catabrosa aquatica, the spikelets of which contained from two to seven flowers.[391]