Geraniaceae
Encyclopedia
Geraniaceae is a family of flowering plant
s placed in the order Geraniales
. The family name is derived from the genus Geranium. It includes both the genus Geranium
(the cranesbills) and the garden plants called geraniums, which modern botany
classifies as genus Pelargonium
, along with other related genera.
There are around 800 species
in the family, distributed in from 7 to 10 genera, according to the database of the Royal Botanic Gardens, Kew
. Numerically, the most important genera are Geranium (430 species), Pelargonium
(280 species) and Erodium
(80 species).
Most species are found in temperate or warm temperate regions, though some are tropical. Pelargonium
has its centre for diversity in the Cape
region in South Africa
, where there is a striking vegetative and floral variation.
region of South America
, is considered the sister to the rest of the family. Some authors separate Hyspeocharis as a monogenic family Hypseocharitaceae, while older sources placed it in the Oxalidaceae
.
The genus Rhynchotheca has also been separated into the Vivianiaceae
.
Geraniaceae are herbs or subshrubs. The Sarcocaulon are succulent
, but other members of the family generally are not.
Leaves are usually lobed or otherwise divided, sometimes peltate
, opposite
or alternate
and usually have stipule
s.
The flower
s are generally regular, or symmetrical. They are hermaphrodite
, actinomorphic (radially symmetrical, like in Geranium) or slightly zygomorphic (with a bilateral symmetry, like in Pelargonium). The calyx and the corolla are both pentamerous (with five lobes), petal
s are free while sepal
s are connate or united at the base. The androecium consists in two whorls of five stamen
s each, some of which can be unfertile; the pistil consists of five (less commonly three) merged carpels. The linear stigma
s are free, and the ovary is superior. Flowers are usually grouped in cymes (e. g. in Geranium), umbel
s (e. g. in Pelargonium
) or, more rarely, spikes.
Geraniaceae are normally pollinated by insects
, but self-pollination
is not uncommon.
The fruit
is a unique schizocarp
made of five (or three) achenes, in the lower part the achenes are inside the calyx, while the upper part (the stylar beak) is the style of the flower, looking like a kind of long beak over the achenes. When the fruit is mature the style breaks into five (or three) hygroscopically active (ready to absorb water) bristles that curl, causing the achenes to be released.
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s placed in the order Geraniales
Geraniales
Geraniales are a small order of flowering plants, included within the rosid subgroup of dicotyledons. The largest family in the order is Geraniaceae with over 800 species. In addition, the order includes some small families, contributing together another less than 40 species...
. The family name is derived from the genus Geranium. It includes both the genus Geranium
Cranesbill
Geranium is a genus of 422 species of flowering annual, biennial, and perennial plants that are commonly known as the cranesbills. It is found throughout the temperate regions of the world and the mountains of the tropics, but mostly in the eastern part of the Mediterranean region. The long,...
(the cranesbills) and the garden plants called geraniums, which modern botany
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...
classifies as genus Pelargonium
Pelargonium
Pelargonium is a genus of flowering plants which includes about 200 species of perennials, succulents, and shrubs, commonly known as scented geraniums or storksbills. Confusingly, Geranium is the correct botanical name of a separate genus of related plants often called Cranesbills. Both Geranium...
, along with other related genera.
There are around 800 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in the family, distributed in from 7 to 10 genera, according to the database of the Royal Botanic Gardens, Kew
Royal Botanic Gardens, Kew
The Royal Botanic Gardens, Kew, usually referred to as Kew Gardens, is 121 hectares of gardens and botanical glasshouses between Richmond and Kew in southwest London, England. "The Royal Botanic Gardens, Kew" and the brand name "Kew" are also used as umbrella terms for the institution that runs...
. Numerically, the most important genera are Geranium (430 species), Pelargonium
Pelargonium
Pelargonium is a genus of flowering plants which includes about 200 species of perennials, succulents, and shrubs, commonly known as scented geraniums or storksbills. Confusingly, Geranium is the correct botanical name of a separate genus of related plants often called Cranesbills. Both Geranium...
(280 species) and Erodium
Erodium
Erodium is a genus of the botanical family Geraniaceae. The genus includes about 60 species, for the most part originating in the Mediterranean or Western Asian regions...
(80 species).
Most species are found in temperate or warm temperate regions, though some are tropical. Pelargonium
Pelargonium
Pelargonium is a genus of flowering plants which includes about 200 species of perennials, succulents, and shrubs, commonly known as scented geraniums or storksbills. Confusingly, Geranium is the correct botanical name of a separate genus of related plants often called Cranesbills. Both Geranium...
has its centre for diversity in the Cape
Cape Province
The Province of the Cape of Good Hope was a province in the Union of South Africa and subsequently the Republic of South Africa...
region in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, where there is a striking vegetative and floral variation.
Taxonomy
Hypseocharis, with between one and three species, which comes from the south-west AndeanAndes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
region of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, is considered the sister to the rest of the family. Some authors separate Hyspeocharis as a monogenic family Hypseocharitaceae, while older sources placed it in the Oxalidaceae
Oxalidaceae
The Oxalidaceae, or wood sorrel family, are a small family of eight genera of herbaceous plants, shrubs and small trees, with the great majority of the 900 species in the genus Oxalis...
.
The genus Rhynchotheca has also been separated into the Vivianiaceae
Vivianiaceae
Vivianiaceae is a family of flowering plants placed in the order Geraniales. The family name is derived from the genus Viviania Cav. It includes both the genus Viviania and genus Caesarea Cambess....
.
Description
Succulent plant
Succulent plants, also known as succulents or fat plants, are water-retaining plants adapted to arid climates or soil conditions. Succulent plants store water in their leaves, stems, and also in roots...
, but other members of the family generally are not.
Leaves are usually lobed or otherwise divided, sometimes peltate
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
, opposite
Phyllotaxis
In botany, phyllotaxis or phyllotaxy is the arrangement of leaves on a plant stem .- Pattern structure :...
or alternate
Phyllotaxis
In botany, phyllotaxis or phyllotaxy is the arrangement of leaves on a plant stem .- Pattern structure :...
and usually have stipule
Stipule
In botany, stipule is a term coined by Linnaeus which refers to outgrowths borne on either side of the base of a leafstalk...
s.
The flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s are generally regular, or symmetrical. They are hermaphrodite
Hermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
, actinomorphic (radially symmetrical, like in Geranium) or slightly zygomorphic (with a bilateral symmetry, like in Pelargonium). The calyx and the corolla are both pentamerous (with five lobes), petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...
s are free while sepal
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s are connate or united at the base. The androecium consists in two whorls of five stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s each, some of which can be unfertile; the pistil consists of five (less commonly three) merged carpels. The linear stigma
Gynoecium
Gynoecium is most commonly used as a collective term for all carpels in a flower. A carpel is the ovule and seed producing reproductive organ in flowering plants. Carpels are derived from ovule-bearing leaves which evolved to form a closed structure containing the ovules...
s are free, and the ovary is superior. Flowers are usually grouped in cymes (e. g. in Geranium), umbel
Umbel
An umbel is an inflorescence which consists of a number of short flower stalks which are equal in length and spread from a common point, somewhat like umbrella ribs....
s (e. g. in Pelargonium
Pelargonium
Pelargonium is a genus of flowering plants which includes about 200 species of perennials, succulents, and shrubs, commonly known as scented geraniums or storksbills. Confusingly, Geranium is the correct botanical name of a separate genus of related plants often called Cranesbills. Both Geranium...
) or, more rarely, spikes.
Geraniaceae are normally pollinated by insects
Entomophily
Entomophily is a form of pollination whereby pollen is distributed by insects. Several insect are reported to be responsible for the pollination of many plant species, particularly bees, Lepidoptera , wasps, flies, ants and beetles. Some plant species co-evolved with a particular pollinator, such...
, but self-pollination
Self-pollination
Self-pollination is a form of pollination that can occur when a flower has both stamen and a carpel in which the cultivar or species is self fertile and the stamens and the sticky stigma of the carpel contact each other in order to accomplish pollination...
is not uncommon.
The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
is a unique schizocarp
Schizocarp
A schizocarp is a dry fruit that develops from multiple carpels. When mature it splits up into mericarps. Mericarps are often 1-seeded as in, for example, Malva, Malvastrum, and Sida...
made of five (or three) achenes, in the lower part the achenes are inside the calyx, while the upper part (the stylar beak) is the style of the flower, looking like a kind of long beak over the achenes. When the fruit is mature the style breaks into five (or three) hygroscopically active (ready to absorb water) bristles that curl, causing the achenes to be released.