Some doubts also exist as to the nature of the beak or columella of such fruits as those of _Geraniaceae_, _Malvaceae_, _Umbelliferae_, _Euphorbiaceae_, &c. The nature of the organ in question may probably be different in the several orders named; at any rate the subject cannot be discussed in this place, and it is mentioned here because, now and then, it happens that the organ in question is completely wanting, and hence affords an illustration of suppression. FOOTNOTES: [464] 'Theorie de la feuille.' p. 24. CHAPTER II. SUPPRESSION OF FOLIAR ORGANS. This subject may be considered, according as the separate leaves of the stem or of the flower are affected, and according as either the number of members of distinct whorls, or that of the whorls themselves, is diminished. The terms aphylly, meiophylly, and meiotaxy may be employed, according as the individual leaves are altogether wanting, or with reference to the diminished number of parts in a whorl, or a decrease in the verticils. =Aphylly.=--Entire suppression of the leaves is a rare phenomenon. Under ordinary circumstances it occurs in most _Cactaceae_, in some of the succulent Euphorbias, and other similar plants, where the epidermal layers of the stem fulfil the functions of leaves. But even in these plants leaf-like organs are present in some stage or another of the plant's life. Partial suppression of the leaf occurs sometimes in compound leaves, some or other of the leaflets of which are occasionally suppressed. Sometimes, as Moquin remarks, it is the terminal leaflet which is wanting, when the appearance is that of _Cliffortia_, at other times the lateral leaflets are deficient, as in _Citrus_ or _Phyllarthron_. _Ononis monophylla_ and _Fragaria monophylla_ may be cited as instances of the suppression of the lateral leaflets. If the blade of the leaf disappears entirely, we have then an analogous condition to that of the phyllodineous acacias. With reference to the strawberry just mentioned, Duchesne, 'Hist. Nat. Frais.,' p. 133, says that this was a seedling raised from the _fraisier des bois_, and the characters of which were reproduced by seed, and have now become fixed. The monophyllous condition has been considered to be the result of fusion of two or more leaflets, but however true this may be in some cases, it is not the case with this strawberry. M. Paillot states that he has found the variety in a wild state.[465] In like manner varieties of the following plants occur with simple leaves, _Rosa berberifolia_ (_Lowea_), _Rubus Idaeus_, _Robinia pseudacacia_, _Fraxinus excelsior_, _Sambucus nigra_, _Juglans nigra_, &c. In one instance seen by the writer every portion of the leaf of a rose was deficient, except the stipules and a small portion of the petiole. (See abortion.)