Papers in the Biological Sciences
Date of this Version
DeCandolle, the author of Calyciflorae, gives the following characters (Prodromus, 2: 1): “Calyx gamosepalous, that is, the sepals more or less united at the base. Torus more or less adnate to the bottom of. the calyx. Petals and stamens inserted on a torus which is partly adnate to the calyx, and therefore geuerally said to be borne on the calyx. Petals free or united with each other. Ovary free, or adnate to the calyx.”
What has generally been regarded as the lower portion of the gamosepalous calyx, and is described as such in many recent systematic works, is in reality the hollow upper portion of the receptacle. In this work the term receptacular-cup (receptacular-tube) has been adopted, a term which indicates the true nature of the organ. The foregoing description may, therefore, be modified to read: “Receptacle broadened into a flat or more or less concave or even tubular calyx-like structure, bearing on its margin the sepals, petals. and stamens, which are free or seldom more or less united; ovaries free, united with each other, or even imbedded in the hollow receptacle."
Bentham and Hooker modified the Candollean Calyciflorae, taking out the families constituting the sub-orders Celastrales and Sapindales, and making of these and the orders Geraniales and Olacales, the series Disciflorae. Hooker gives the reason for so doing in his edition of LeMaout and Decaisne, p. 993: "The great obstacle to the recognition of the thalamifloral and calycifloral series lies in the fact that (putting aside the many cases of hypogynous orders containing perigynous genera) there are many orders of which it is difficult to say to which they belong. Thus Brongniart regards as hypogynous Anacardiaceae, Connaraceae, Burseraceae, and Celastraceae, all of which are regarded as perigynous by DeCandolle; and as perigynous, Caryophylleae, Elatineae, and Olacineae, which DeCandolle and Lindley regard as hypogynous. To reduce this difficulty, Mr. Bentham and I, observing that a highly developed staminiferous disk prevailed in the orders that intervened between the manifestly perigynous and hypogynous orders, collected them into a division of Polypetalae called series Disciflorae. In doing this we did not look on the disk as a proof of affinity, but as a guide to that amount of affinity which certainly exists between the orders included under that series."
The difficulty seems to have been remedied very little, however. Whatever relationship there may be between the Geraniales and Celastrales, there is a much nearer one between the former and the Caryophyllales. Linaceae among the Geraniales is in the closest relationship to Caryophyllaceae, from which it differs mainly in the position of the ovules. The affinities of the Celastrales are nearly all among the calycifloral families. Rhamnaceae and Celastraceae are nearly related to groups of plants now generally included in Saxifragaceae, but formerly placed in either of those families.
The systematic position of the Umbellales has been very uncertain. While their close relationship to the Rubiales among the Gamopetalae has been recognized, indeed, strongly emphasized, their affinities among the other calycifloral orders have been very uncertain. The isostemonous flowers, the few, united, 1-2-ovuled carpels, the copious albumen, and the generally thick, fleshy disk at the margin of which the stamens are fastened are all characters common to the Umbellales and the Celastrales. The difference between the two is rather of degree than of kind. In the Celastrales, the ovary is generally superior, in the Umbellales, inferior, i. e., sunken into the receptacle. But, in some genera of Rhamnaceae and Celastraceae, the ovary is partly sunken in the receptacle, scarcely less so than in some representatives of Araliaceae, as for instance, Hedera helix.
If the fleshy disk that gave the name to the Disciflorae is used as the characteristic feature of the series,the Umbellales should be included in Disciflorae, and the Geraniales excluded, as the disk, if present, is of a different character. If, however, it is to take in the families on the border line between the Thalamiflorae and the Calyciflorae, then such families should be included as Crassulaceae and Saxifragaceae proper, in which the calycifloral character is generally obsolete. This is also the case in many genera in most families of the Rosales. It is, therefore, best to leave Calyciflorae as originally constituted.
Lincoln, Neb., 1895