Ranunculaceae


Ranunculaceae is a family of over 2,000 known species of flowering plants in 43 genera, distributed worldwide.
The largest genera are Ranunculus, Delphinium, Thalictrum, Clematis, and Aconitum.

Description

Ranunculaceae are mostly herbaceous annuals or perennials, but some are woody climbers or shrubs.
Most members of the family have bisexual flowers which can be showy or inconspicuous. Flowers are solitary, but are also found aggregated in cymes, panicles, or spikes. The flowers are usually radially symmetrical but are also found to be bilaterally symmetrical in the genera Aconitum and Delphinium. The sepals, petals, stamens and carpels are all generally free, the outer flower segments typically number four or five. The outer stamens may be modified to produce only nectar, as in Aquilegia, Helleborus and Delphinium.
In some genera, such as Thalictrum, the sepals are colorful and appear petal-like and the petals can be inconspicuous or absent. The stems are unarmed. The leaves are variable. Most species have both basal and cauline leaves, which are usually compound or lobed but can be simple. They are typically alternate, or occasionally opposite or even whorled. Many species, especially the perennials, form rhizomes that develop new roots each year. Ficaria verna can reproduce vegetatively by means of root tubers produced in the leaf axils. Some members of the genus Thalictrum utilize anemophily while others utilize entomophily. Flowers of the entomophilous genus Papaver, also of the Ranunculales order, produce only pollen. Until recently, it was believed that the species of the genus Anemone also lack nectar.
The fruits are most commonly free, unfused achenes or follicles, but a berry in Actaea.

Phytochemistry

Many Ranunculaceae members contain protoanemonin, which is toxic to humans and animals. Contact with plant sap may cause inflammation and blistering of the skin, while ingestion can cause irritation of the mouth, vomiting, and diarrhea.
Toxic alkaloids such as aconitine may also be present in some species such as Aconitum carmichaelii.

Taxonomy

Takhtajan included the Ranunculaceae as the only family in the Ranunculales which he placed in a subclass, the Ranunculidae, instead of a superorder. Previously, Thorn placed the Ranunculaceae in the Berberidales, an order within the Superorder Magnolianae. Earlier Cronquist in 1981 included the Ranunculaceae along with seven other families in the Rancunculales which was included in the Magnoliidae, which he regarded as a subclass. David, placed the Ranuculaceae, together with the Eupteleaceae, Lardizabalaceae, Menispermaceae, Berberidaceae, and Papaveraceae in the Ranunculales, the only order in the superorder Ranunculanae. This follows the work of the Angiosperm Phylogeny Group.
The family Ranunculaceae sensu stricto is one of seven families included in the order Ranunculales within the eudicots according to the Angiosperm Phylogeny Group classification. The family is monophyletic with Glaucidium as sister to the remaining genera. This phylogeny is illustrated in the APG Poster.

Subdivision

Early subdivisions of the family, such as Michel Adanson, simply divided it based on one-seeded or many-seeded fruit. Prantl envisaged three tribes, Paeonieae, Helleboreae and Anemoneae with Paeonia, Glaucidium and Hydrastis forming Paeonieae. By the twentieth century Langlet used chromosome types to create two subfamilies, Ranunculoideae and Thalictroideae. In 1966, Tamura further developed Langlet's system by adding floral characteristics with six subfamilies;
  • Helleboroideae
  • Ranunculoideae
  • Isopyroideae
  • Thalictroideae
  • Coptidoideae
  • Hydrastidoideae
but by 1988 he had reduced Coptidoideae to a tribe within Isopyroideae, leaving five subfamilies, an arrangement he continued in his 1993 monograph, dividing the larger subfamilies into tribes, though by then Paeonia and Glaucidium were no longer considered to belong to Ranunculaceae. Paeonia was separated from Ranuculaceae and placed in its own family of Paeoniaceae. Other genera originally included in Ranunculaceae include Circaeaster, which was placed in its own family Circaeasteraceae.
Tamura's complete system was structured as follows;
;Subfamilies and tribes
  • Subfamily Ranunculoideae Hutch.
  • * Adonideae Kunth
  • * Anemoneae DC.
  • * Ranunculeae DC.
  • Subfamily Helleboroideae Hutch.
  • * Helleboreae DC.
  • * Cimicifugeae Torrey & A.Gray
  • * Delphineae Schrödinger
  • * Nigelleae Schrödinger
  • Subfamily Isopyroideae Tamura
  • * Coptideae Langlet ex Tamura & K.Kosuge
  • * Dichocarpeae Tamura & K.Kosuge
  • * Isopyreae Schrödinger
  • Subfamily Thalictroideae
  • Subfamily Hydrastidoideae
The genus Glaucidium, having been moved to its own family, has since been restored to Ranuculaceae.

Molecular phylogenetics

When subjected to molecular phylogenetic analysis, only Thalictroideae is monophyletic. The position of Glaucidium and some of its unique morphological characteristics prompted Stevens to suggest that it be given subfamilial rank as the monotypic Glaucidioideae. Similarly, Hydrastis has been assigned to subfamily Hydrastidoideae. Both genera are represented by a single species, Glaucidium palmatum and Hydrastis canadense respectively.
The relationships between the genera suggest the existence of three major clades corresponding to Coptidoideae, Thalictroideae and Ranunculoideae. The latter is the largest with four subclades. Of these, C corresponds to Delphineae, D to Cimicifugae and E to Ranunculoideae. Consequently, Wang and colleagues proposed a new classification with five subfamilies, and further subdividing Ranunculoideae into ten tribes. The relationship between the subfamilies is shown in the cladogram
In addition to the two monotypic subgenera, Coptoideae has 17 species and Thalictroideae has 450, including Thalictrum and Aquilegia. The other genera belong to Ranunculoideae. Kingdonia had been included by Tamura in Anemoneae, but is now added to Circaeasteraceae.
In recent years, researchers have used nuclear genes to further investigate the phylogenetic relationships of the Ranunculaceae family, and their findings are consistent with those of Wang and colleagues. However, this study indicates that the ancestors of the Ranunculaceae family experienced multiple whole-genome duplication events, which may be related to the longstanding prosperity of this ancient group.
;Subfamilies of Ranunculaceae and tribes of Ranunculoideae
  • Glaucidioideae Loconte
  • Hydrastidoideae Engler
  • Coptidoideae Tamura
  • Thalictroideae Raf.
  • Ranunculoideae Arn.
  • * Adonideae Kunth
  • * Delphinieae Schröd.
  • * Nigelleae Schröd.
  • * Helleboreae DC.
  • * Cimicifugeae Torr. and A.Gray
  • * Caltheae Bercht. and J.Presl
  • * Asteropyreae W.T.Wang and C. Y.Chang
  • * Callianthemeae W.Wang and Z. D.Chen
  • * Anemoneae DC.
  • * Ranunculeae DC.

    Genera

Ranunculaceae contains approximately 43 genera.
; Subfamily Glaucidioideae
  • Glaucidium Siebold & Zuccarini
; Subfamily Hydrastidoideae
  • Hydrastis L.
; Subfamily Coptidoideae
  • Coptis Salisb.
  • Xanthorhiza Marshall
; Subfamily Thalictroideae
  • Aquilegia L.
  • Dichocarpum W.T.Wang & P.K.Hsiao
  • Enemion Rafinesque
  • Isopyrum L.
  • Leptopyrum Reichenbach
  • Paraquilegia J.R.Drumm. & Hutch.
  • Semiaquilegia Makino
  • Thalictrum L.
  • Urophysa Ulbr.
; Subfamily Ranunculoideae
;; Tribe Adonideae
  • Adonis L.
  • Calathodes Hook.f. & Thomson
  • Megaleranthis Ohwi
  • Trollius L.
;; Tribe Delphinieae
  • Aconitum L.
  • Consolida Gray
  • Gymnaconitum Wei Wang & Z.D.Chen
  • Delphinium L.
  • Staphisagria Hill
;; Tribe Nigelleae
  • Nigella L.
;; Tribe Helleboreae
  • Helleborus L.
;; Tribe Cimicifugeae
  • Actaea L.
  • Anemonopsis Siebold & Zuccarini
  • Beesia Balf.f. & W.W.Sm.
  • Cimicifuga Wernisch.
  • Eranthis Salisb.
;; Tribe Caltheae
  • Caltha L.
;; Tribe Asteropyreae
  • Asteropyrum J.R.Drumm. & Hutch.
;; Tribe Callianthemeae
  • Callianthemum C.A.Mey.
;; Tribe Anemoneae
  • Anemoclema W.T.Wang
  • AnemonastrumHolub
  • Anemone L.
  • Anemonoides Mill.
  • Clematis L.
  • Eriocapitella Nakai
  • Hepatica Mill.
  • Knowltonia Salisb.
  • Metanemone W.T.Wang
  • Naravelia Adans.
  • Pulsatilla Mill.
;; Tribe Ranunculeae
  • Arcteranthis Greene
  • Beckwithia Jeps.
  • Callianthemoides Tamura
  • Ceratocephala Moench
  • Coptidium Á.Löve & D.Löve ex Tzvelev
  • Cyrtorhyncha Nutt.
  • Ficaria Guett.
  • Halerpestes Greene
  • Hamadryas Comm. ex Juss.
  • Krapfia DC.
  • Kumlienia Greene
  • Laccopetalum Ulbr.
  • Myosurus L.
  • Oxygraphis Bunge
  • Paroxygraphis W.W.Sm.
  • Peltocalathos Tamura
  • Ranunculus L.
  • Trautvetteria Fisch. & C.A.Mey.
Previous genera
  • Anemonella Spach → Thalictrum
  • Psychrophila Bercht. & J.Presl → ''Caltha''

    Fossil record

Contrary to earlier data, there are no confirmed pre-Tertiary ranunculacean fossils. The Early Cretaceous Leefructus mirus from the Yixian Formation in China was described as belonging to the "compare Family stem lineage to the Ranunculaceae". The oldest confirmed representative of the family is Paleoactaea nagelii Pigg & DeVore described on the basis of fruits coming from the Upper Paleocene of North Dakota.