''Menodora'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

perennial plant A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

s and

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

s in the olive family

Oleaceae Oleaceae, also known as the olive family, is a taxonomic family of flowering shrubs, trees, and a few lianas in the order Lamiales, It presently comprises 28 genera, one of which is recently extinct.Peter S. Green. 2004. "Oleaceae". pages 296-30 ...

. Its 23 species (as per Green 2003) are found in the temperate

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

and in southern

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

. These are uniform species of deserts and arid grasslands or savannas.

Description

The usually bisexual flowers have a united

calyx Calyx or calyce (plural "calyces"), from the Latin ''calix'' which itself comes from the Ancient Greek ''κάλυξ'' (''kálux'') meaning "husk" or "pod", may refer to: Biology * Calyx (anatomy), collective name for several cup-like structures ...

with 5-10 lobes (rarely more), while the corolla is similarly united but with 4-6 lobes. The corolla is a pretty, bright yellow (except for ''M. spinescens'', whose corollas are white), and is often scented. The fruit is a didymous, bilobed capsule with each globose

locule A locule (plural locules) or loculus (plural loculi) (meaning "little place" in Latin) is a small cavity or compartment within an organ or part of an organism (animal, plant, or fungus). In angiosperms (flowering plants), the term ''locule'' usu ...

or lobe containing 2-4 seeds. In the majority of species, each locule also features circumscissile dehiscence. Vegetatively, the plants are generally unremarkable, with a "green-stick" look that is common to many desert plants. In the dry seasons, plants may lose their generally small or reduced leaves altogether. Leaf shape within the genus is highly variable, ranging from short and linear to almost feathery and pinnatisect. Leaves are most commonly found arranged in opposite pairs, but in some individuals may be predominantly alternate.

Etymology

Willis Jepson mistakenly suggested that the origin of the genus name was rather obscure, perhaps deriving from the Greek for "half-moon spear" for the appearance of the dehisced fruit on its pedicel. In reality, the name was specifically derived from the Greek μενος (''menos''), meaning "force," and δωρον (''doron''), meaning "gift," referring to the sustenance the plants provided to the horses of Humboldt and Bonpland (1809) when they first encountered the genus in the present state of Hidalgo in Mexico.

Selected species

Taxonomy

'' Menodora longiflora'' has occasionally been treated as the monotypic genus ''Menodoropsis'' (Small, 1903) due to the extraordinary length of its corolla tube (to nearly 6 cm, as opposed to typical lengths of 0.3 to 0.7 cm in most other species), but based on both morphological and molecular data it plainly belongs within ''Menodora''. Small took the name for the genus from one of the sections of the ''Menodora'' recognized by Asa Gray (1852). Neither the sectional classification of Gray (1852) nor Steyermark (1932) have been upheld by recent molecular studies. One of the more distinctive things about this genus is the pattern of disjunction or non-continuous distribution. In the

, the distribution jumps over the tropics, with only a few species whose individual distributions just cross into the tropics (e.g., north to central

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

, and south to

Oaxaca Oaxaca ( , also , , from nci, Huāxyacac ), officially the Free and Sovereign State of Oaxaca ( es, Estado Libre y Soberano de Oaxaca), is one of the 32 states that compose the political divisions of Mexico, Federative Entities of Mexico. It is ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

). This is a common pattern found in many genera, but not many others with a similar amphitropical distribution also have connections across the

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

with

. This intercontinental distribution of ''Menodora'' was often cited as evidence of continental drift or the breakup of the Pangaea or

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

n supercontinents, but more recently it has been judged to be the result of long distance dispersal.

References

{{Taxonbar, from=Q2712889 Oleaceae genera Taxa named by Aimé Bonpland Taxa named by Alexander von Humboldt