!29 



INFLORESCENCE. 



INFLORESCENCE. 



230 



P. puitulosa is a native of the Indian seas, where the other species 

 have also been found. 



Phyllidia pustulom, 



Dipliyllidia (LingueUa, ? Leach). Eranchia?, nearly the same as in 

 PhyUidia, but the mantle is more pointed behind ; the head, which 

 is demieircular (la tete, en demi-cercle), haa on each side a pointed 

 tentacle and a slight tubercle ; vent on the right side. (Cuvier.) 



M. De Blainville thus describes Linguella, which both Cuvier and 

 himself seem to consider as identical with Diphyllidia. 



Body oval, very much depressed, the mantle projecting beyond the 

 foot on all sides, except in front ; head uncovered. Branchial lamella? 

 oblique, and only occupying the two posterior thirds of the inferior 

 border of the mantle ; vent inferior, situated at the posterior third 

 of the right side ; orifices of the organs of generation in the same 

 tubercle, at the anterior third of the same side. 



Linyuella Elfortii, De Blainv. (Diphyllidia Brugmansii ? Cuv.). 

 M. De Blainville says that the locality of this animal is unknown. 

 Cuvier nays that Linyuella Elfortii appears to him not to be different 

 from hia Diphyllidia Brugmantii. 



M. De Blainville further says that it is probable that the genus 

 established by M. Raflnesque under the name of Arminia does not 

 differ much from Linguella. In his 'Additions and Corrections' to 

 his ' Manuel ' he says that M. Otto has discovered a species of Linyudla 

 in the sea of Naples. 



lAnguella Elfortii. De Blainville. 



M. Rang observes that Diphyllidia, Languella, and Arminia being 

 identical, Cuvier's came should be preserved : the two subsequent 

 names should consequently be omitted. 



Messrs. Forbes and Hanley, in the Appendix to the ' History of 

 British Mollusca," give an account of the taking of specimens of 

 Diphyllidia lineata in the Shetland Isles and at Whitburn in Durham. 



M. Rang included the fresh-water Aucyliu in this group. It has 

 however pulmonic sacs, and belongs to the Limneadce. 



INFLORESCENCE, in Plants, is the manner in which their flowers 

 are arranged. A flower being a body analogous to a leaf-bud, with a 

 similar origin, and capable, under particular circumstances, of revert- 

 ing absolutely to that condition, it follows that the branching of that 

 part of a plant which bears flowers should be of the same nature as that 

 which bears leaf-buda, and therefore not in need of special explanation. 

 But as the formation of the flower out of the materials of a leaf-bud 

 is accompanied with many deviations from the habitual development 

 of its parts, so is the disposition of the branches of inflorescence often 

 in a similar way a deviation from the habitual method of arranging 

 those parts. 



In the study of the inflorescence of plants it should never be 

 forgotten that it is entirely dependent on modifications of the axis. 

 For the purposes of arrangement it may be considered as regular or 

 centripetal, and irregular or centrifugal : in the former all the parts 

 are formed successively without interruption ; iu the latter the parts 

 are subject to various interruptions and derangements in the progress 

 of their formation. In centripetal inflorescence the external flowers 



of a disc, or the lowermost of a cone, are first developed, and con- 

 sequently first expanded ; nnd hence the course of unfolding proceeds 

 from the circumference to the centre, or, which is the same thing, 

 from the base to the apex. In centrifugal inflorescence the axis of 

 growth i arrested iu its progress by the formation of a flower-bud, 

 a at a, in the accompanying diagram ; two lateral points then develop 

 from below a, and lengthen to 6, where a new flower-bud appears, 

 and stop* the growth ; two other lateral points are produced from 



below b and lengthen to c, where a new flower-bud again arrests the 

 progress of development ; and so on. In this case it is clear that a 

 in the centre, being first formed, will expand before b b and c c c c ; 

 that b b will in like manner open before c c c c, and in the same way 

 all the others : hence the order of expansion of the flowers is from 

 the centre to the circumference. To this kind of inflorescence the 

 word Cyme is usually applied. It occurs in the Common Elder, the 

 Laurustinue, &c. 



The centripetal inflorescence, in its simplest state, is merely a branch 

 bearing flowers instead of leaf -buds, as in the Hyacinth nnd the Omi- 

 thogalum. If the flowers are sessile, it is then called a Spike ; if 

 stalked, a Raceme. If the branch of the spike or its axis is so much 

 contracted as to become a broad disc, as in the Dandelion, or Daisy, 

 or common Artichoke, the inflorescence is called a Head or Capitulum ; 

 if the same thing happens to a raceme, the Umbel of Astrautia, Fennel, 

 Parsley, &c., is the result. Let the flower-stalks of the raceme be 

 branched or racemose, and the Panicle is produced. 



The following is a survey of the kinds of inflorescence and their 

 names, from Professor Schleiden's ' Principles of Scientific Botany.' 



A. The Solitary Flower, as terminal or axillary flower (Flos Solitarius, 

 terminalis vel axillaris). The latter may be situated in whorls, and 

 then form a Verticil (Verticillus). 



B. Simple Inflorescence. 

 o. Inflorescentia Centripeta. 



1. The Capitulum. The undeveloped axis is here usually enlarged 

 upward, with a fleshy or spongy substance, and the more so if the 

 number of flowers is very great. It may be more minutely designated 

 as simple, discoid, cupulate, lageniform, conical, and cylindrical, as 

 it approaches nearer to one or another. The last form then passes 

 gradually into the spadix. Special varieties are : 



* The Calathium (Anthodium, Ehrh. ; Flos Composittts, Linn.), a 

 many-flowered Capitulum, whose single flowers stand in the axils of 

 more or fewer stunted bracts, and are surrounded with one or more 

 circles of sterile bracts, as in the family of the Composite. 



** The Cxnanthinum, Nees (Hypanthodium, Link.). Exactly like 

 the preceding inflorescence in some Urticacea. The cup-shape of the 

 peduncle in Picus is no distinction, since it is wanting in Dorstenia ; 

 and it exists in some Composite ; the same may be said with regard 

 to the sterile bracts, which are as much stunted in Dorstenia as they 

 are clearly present in Ficus. 



2. The Spike (Spica) in very various forms. The kinds are : 



* The Catkin (Amentum), distinguished by the fact that it falls off 

 entire, or by its imperfect flowers. The male inflorescence of Cupuli- 

 ferae, Salicacece, Betulacece, and some few other plants. 



** The Spadix, a closely crowded spike, or partially a cylindri- 

 cal capitulum with fleshy peduncle ; in Aracece, Maize, and some other 

 Grasses, and in Palms, in the last of which it is often compound 

 (Spadix Ramosus). 



*** The Cone (Strobilus or Conus), a cylindrical capitulum or 

 solid spike, on which the individual foliar organs become woody scales ; 

 as in the font/era, the Catuarinacea, the BeMaceai, and some others. 



* The Spikelet (Spicula), the simple inflorescence of the Grasses 

 and Cyperacece ; namely, a few-flowered spike, whose flowers have no 

 bracts, surrounded at the basis by one or two sterile bracts (Gluina;). 



3. The Umbel (Umbella) in the Umbelliferce ; when compound 

 termed Umbellule (Umbellula). 



4. The Raceme (Racemus) occurs in very different forms ; it is 

 usual to distinguish in it 



The Corymb (Corymbus), a pyramidal raceme. 

 . Inflorescentia Centrifuga. 



6. The Cyme or False Umbel (Cyma), is a corymb with Inflows- 

 centia Centrifuga. 



That only singular cases are distinguished in these is a proof of the 

 totally unscientific patching together of our terminology. The com- 

 pound raceme, the compound umbel, and capitulum, with inflorescentia 

 Centrifuga are all called a Cyme (Cyma), which is contrary to the 

 commonest scientific laws. De Candolle has further applied the term 

 Cyme to the inflorescence of the Boraginace, which, on account of 

 the peculiar manner in which it unrolls itself, he terms Cyma Scor- 

 pioides ; and he adds the fiction, that the undermost first-blooming 

 flower is really the terminal blossom, and the second, the terminal 

 blossom of side axis, is developed in a disproportionate degree, &c. 

 From the rolling up there is just as little to be deduced as from the 

 same phenomenon in the leaves of 1'icus and Cycadaccce. The posi- 

 tion of the bracts, as seen in Cerinthe, contradicts this fiction ; and 

 the history of the development, which can alone determine the point, 

 appears to prove that here a one-sided raceme or spike is present, whose 

 unrolling is only a peculiar situation of the buds. 



C. Once-Compound Inflorescence, 

 a. Pure or Homomorphous. 

 * Inflorescentia Centripeta. 



6. The Spike of the Grasses (Spica), several spikes united in a 

 spicate arrangement, as in the Grasses; the component npikm are 

 termed Spikelets (Spiculse). 



