Hydnoraceae is a family of parasitic flowering plant

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 in the order Piperales

Piperales

Piperales is a botanical name for an order of flowering plants. It necessarily includes the family Piperaceae but otherwise has been treated variously over time...

. It contains two genera, Hydnora and Prosopanche and some seven species. Prosopanche contains two species from Central and South America and Hydnora contains five species from arid areas of Africa, Saudi Arabia, and Madagasgar.

Description

The most striking aspect of the Hydnoraceae is probably the complete absence of leaves (not even in modified forms such as scales). Some species are mildly thermogenic

Thermogenic plants

Thermogenic plants have the ability to raise their temperature above that of the surrounding air. Heat is generated in the mitochondria, as a secondary process of cellular respiration called thermogenesis...

 (capable of producing heat), presumably as a means to dispersing their scent.

Ecology

The plants are pollinated by insects such as dermestid beetles or carrion flies, attracted by the fetid odor of the flowers. In Hydnora africana

Hydnora africana

Hydnora africana is an achlorophyllous plant native to southern Africa that is parasitic on the roots of members of the Euphorbiaceae family. The plant grows underground, except for a fleshy flower that emerges above ground and emits an odor of feces to attract its natural pollinators, dung...

there are bait bodies with a strong smell, whereas in Hydnora johannis the scent comes from a region at the tip of the perianth

Perianth

The term perianth has two similar but separate meanings in botany:* In flowering plants, the perianth are the outer, sterile whorls of a flower...

 called a cucullus. The flowers may be above ground or underground. The fruits have edible, fragrant pulp, which attracts animals such as porcupine

Porcupine

Porcupines are rodents with a coat of sharp spines, or quills, that defend or camouflage them from predators. They are indigenous to the Americas, southern Asia, and Africa. Porcupines are the third largest of the rodents, behind the capybara and the beaver. Most porcupines are about long, with...

s, monkey

Monkey

A monkey is a primate, either an Old World monkey or a New World monkey. There are about 260 known living species of monkey. Many are arboreal, although there are species that live primarily on the ground, such as baboons. Monkeys are generally considered to be intelligent. Unlike apes, monkeys...

s, jackal

Jackal

Although the word jackal has been historically used to refer to many small- to medium-sized species of the wolf genus of mammals, Canis, today it most properly and commonly refers to three species: the black-backed jackal and the side-striped jackal of sub-Saharan Africa, and the golden jackal of...

s, rhinoceros

Rhinoceros

Rhinoceros , also known as rhino, is a group of five extant species of odd-toed ungulates in the family Rhinocerotidae. Two of these species are native to Africa and three to southern Asia....

, and armadillo

Armadillo

Armadillos are New World placental mammals, known for having a leathery armor shell. Dasypodidae is the only surviving family in the order Cingulata, part of the superorder Xenarthra along with the anteaters and sloths. The word armadillo is Spanish for "little armored one"...

s, as well as humans. The host plants, in the case of Hydnora, generally are in the family Euphorbiaceae

Euphorbiaceae

Euphorbiaceae, the Spurge family are a large family of flowering plants with 300 genera and around 7,500 species. Most are herbs, but some, especially in the tropics, are also shrubs or trees. Some are succulent and resemble cacti....

 and the genus Acacia

Acacia

Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...

. Those for Prosopanche include various species of Prosopis

Prosopis

Prosopis is a genus of flowering plants in the pea family, Fabaceae. It contains around 45 species of spiny trees and shrubs found in subtropical and tropical regions of the Americas, Africa, Western Asia, and South Asia. They often thrive in arid soil and are resistant to drought, on occasion...

and other legume

Fabaceae

The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...

s.

Classification

Like many parasitic plants, the affinities with non-parasitic plants are not obvious, and 19th and 20th century botanists proposed a variety of placements for the family. Molecular data places them in the Piperales

Piperales

Piperales is a botanical name for an order of flowering plants. It necessarily includes the family Piperaceae but otherwise has been treated variously over time...

, more closely related to Aristolochiaceae

Aristolochiaceae

The Aristolochiaceae, or the Birthwort family, are a family of flowering plants with 7 genera and about 400 species belonging to the order Piperales...

 than to Piperaceae

Piperaceae

The Piperaceae, also known as the pepper family, is a large family of flowering plants. The group contains roughly 3,610 currently accepted species in five genera. The vast majority of peppers can be found within the two main genera: Piper and Peperomia .Members of the Piperaceae may be small...

 or Saururaceae

Saururaceae

Saururaceae is a plant family comprising four genera and seven species of herbaceous flowering plants native to eastern and southern Asia and North America. The family has been recognised by most taxonomists, and is sometimes known as the "lizard's-tail family"...

.