''Menodora'' is a
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
perennial plant
In horticulture, the term perennial (''wikt:per-#Prefix, per-'' + ''wikt:-ennial#Suffix, -ennial'', "through the year") is used to differentiate a plant from shorter-lived annual plant, annuals and biennial plant, biennials. It has thus been d ...
s and
shrub
A shrub or 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 by their multiple ...
s in the olive family
Oleaceae
Oleaceae, also known as the olive family or sometimes the lilac 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. Gree ...
. Its 23 species (as per Green 2003) are found in the temperate
Americas
The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...
and in southern
Africa
Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...
. These are uniform species of deserts and arid
grasslands
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes such as clover, and other herbs. Grasslands occur ...
or savannas.
Description
The usually bisexual flowers have a united
calyx
CALYX, Inc. is a non-profit publisher of art and literature by women founded in 1976 based in Corvallis, Oregon. CALYX publishes both '' CALYX, A Journal of Art and Literature by Women'' twice a year and CALYX Books, which publishes one to three ...
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 (: locules) or loculus (; : loculi) 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'' usually refers to a chamber within an ovary ...
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 Humboldt may refer to:
People
* Alexander von Humboldt, German natural scientist, brother of Wilhelm von Humboldt
* Wilhelm von Humboldt, German linguist, philosopher, and diplomat, brother of Alexander von Humboldt
Fictional characters
* Hu ...
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
Americas
The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...
, 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
Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...
, and south to
Oaxaca
Oaxaca, officially the Free and Sovereign State of Oaxaca, is one of the 32 states that compose the political divisions of Mexico, Federative Entities of the Mexico, United Mexican States. It is divided into municipalities of Oaxaca, 570 munici ...
in
Mexico
Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
). 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 oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...
with
Africa
Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...
. This intercontinental distribution of ''Menodora'' was often cited as evidence of
continental drift
Continental drift is a highly supported scientific theory, originating in the early 20th century, that Earth's continents move or drift relative to each other over geologic time. The theory of continental drift has since been validated and inc ...
or the breakup of the
Pangaea
Pangaea or Pangea ( ) was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous period approximately 335 mi ...
or
Gondwana
Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...
n
supercontinent
In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", ...
s, 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