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Bible Encyclopedias
Ranunculaceae
1911 Encyclopedia Britannica
or in botany, a natural order of Dicotyledons belonging to the subclass Polypetalae, and containing 27 genera with about 500 species, which are distributed through temperate and cold regions but occur more especially beyond the tropics in the northern hemisphere. It is well represented in Britain, where 1 i genera are native. The plants are mostly herbs, rarely shrubby, as in Clematis, which climbs by means of the leaf-stalks, with alternate leaves, opposite in Clematis, generally without stipules, and flowers which show considerable variation in the number and development of parts but are characterized by free hypogynous sepals and petals, numerous free stamens, usually many free one-celled carpels (fig. 2) and small seeds containing a minute straight embryo embedded in a copious endorsperm. The parts of the flower are generally arranged spirally on a convex receptacle. The fruit is one-seeded, an achene (fig. 3), or a many-seeded follicle (fig. 4), rarely, as in Actaea, a berry.
From Vines's by permission of Swan, Sonnenschein & Co..
FIG. i. - Gynoecium of Ranunculus: x, receptacle with the points of insertion of the stamens, which have been removed.
The order falls into several distinguished by characters of From Strasburger's Lehrbuck der Botanik, by permission of Gustav Fischer.
FIG. 2. - Ranunculus FIG. 3. - Single FIG. 4. - Fruit of Col arvensis. Carpel in follicle showumbine (Aquilegia) longitudinal section. ing dehiscence formed of five fol (After Baillon, enby the ventral licles.
larged.) suture.
represented among British native or commonly grown garden plants.
Tribe I. Paeonieae, peony group, are mostly herbs with deeply cut leaves and large solitary showy flowers in which the parts are spirally arranged, the sepals, generally five in number, passing gradually into the large coloured petals. The indefinite stamens are succeeded by 2-5 free carpels which bear a double row of ovules along the ventral suture. Honey is secreted by a ring-like swelling round the base of the carpels, which become fleshy or leathery in the fruit and dehisce along the ventral suture. There are only three genera, the largest of which, Paeonia, occurs in Europe, temperate Asia and western North America. P. officinalis is the common peony.
Tribe II. Helleboreae are almost exclusively north temperate or subarctic; there are 15 genera, several of which are represented in the British flora. The plants are herbs, either annual, e.g. Nigella (love-in-a-mist), or perennial by means of a rhizome, as in Aconitum or Eranthis (winter aconite). The leaves are simple, as in Caltha, but more often palmately divided as in hellebore (fig. 6), aconite (fig. 5) and larkspur. The flowers are solitary (Eranthis) or in FIG. 6. - Pedate leaf of StinkingHellebore (Helleborus foetidus). It is a palmately-partite leaf, in which the lateral lobes are deeply divided. When the leaf hangs down it resembles the foot of a bird, and hence the name.
cymes or racemes, and are generally regular as in Caltha (king-cup, marsh marigold), Trollius (globe-flower), Helleborus, Aquilegia (columbine); sometimes medianly zygomorphic as in Aconitum (monkshood, aconite) and Delphinium (larkspur). The carpels, generally 3 to 5 in number, form in the fruit a many-seeded follicle, except in Actaea (baneberry), where the single carpel develops to form a many-seeded berry, and in Nigella, where the five carpels unite to form a five-chambered ovary. There is considerable variety in the form of the floral envelopes and the arrangement of the parts. The outer series, or sepals, generally five in number, is generally white or bright-coloured, serving as an attraction for insects, especially bees, as well as a protection for the rest of the flower. Thus in Caltha and Trollius the sepals form a brilliant golden-yellow cup or globe, and in Eranthis a pale yellow star which contrasts with the green involucre of bracts immediately below it; in Nigella they are blue or yellow, and also coloured in Aquilegia. In Hellebore the greenish sepals persist till the fruit is ripe. A conitum and Delphinium differ in the irregular development of the sepals, the posterior sepal being distinguished from the remaining four by its helmet-shape (Aconitum) or spur (Delphinium). In Caltha there are no petals, but in the other genera there are honey-secreting and storing structures varying in number and in form in the different genera. In Trollius they are long and narrow with a honey-secreting pit at the base, in Nigella and Helleborus (fig. 7) they form short FIG. 7. - Helleborus niger. 1, vertical section of flower; 2, nectary, side and front view (nat. size).
stalked pitchers, in Aquilegia they are large and coloured with a showy petal-like upper portion and a long basal spur in the tip of which is the nectary. In Delphinium they are also spurred, and in Aconitum form a spur-like sac on a long stalk (fig. 8). The parts of the flower are generally arranged in a spiral (acyclic), but are sometimes hemicyclic, the perianth forming a whorl as in winter aconite; rarely is the flower cyclic, as in Aquilegia (fig. 9) where FIG. 8. - Part of the flower of Aconite (Aconitum Napellus), showing two irregular horn-like petals p, supported on grooved stalks o. These serve as nectaries. s, the whorl of stamens inserted on the thalamus, and surrounding the pistil.
the parts throughout are arranged in alternating whorls. In Caltha, where there are no petals, honey is secreted by two shallow depressions on the side of each carpel.
