''Mariosousa heterophylla'', also called the palo blanco tree (which is also applied to '' Ipomoea arborescens''), palo liso, guinola, and Willard acacia, is a normally

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...

mimosoid The Mimosoideae are a traditional subfamily of trees, herbs, lianas, and shrubs in the pea family (Fabaceae) that mostly grow in tropical and subtropical climates. They are typically characterized by having radially symmetric flowers, with petals ...

plant in the genus ''

Mariosousa ''Mariosousa'' is a genus of 13 species of flowering plants in the family Fabaceae. It belongs to the mimosoid clade of the subfamily Caesalpinioideae. Members of this genus were formerly considered to belong to the genus ''Acacia''. Restricte ...

'' native to

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 ...

. The Spanish common name translates into 'white stick', defining its peeling white bark. A compound called willardiine, that acts as an

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

glutamate Glutamic acid (symbol Glu or E; the ionic form is known as glutamate) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can syn ...

receptor Receptor may refer to: * Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a ...

s, can be isolated from ''M. heterophylla''.

Description

It can grow 10–20 ft or more with a spread of to the height. It is a very slender tree with few branches as well as

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

. The petiolar-rachis is characteristically long and functions as a

cladophyll In botany, the petiole () is the stalk that attaches the leaf blade to the stem, and is able to twist the leaf to face the sun. This gives a characteristic foliage arrangement to the plant. Outgrowths appearing on each side of the petiole in so ...

. it has a white or yellow-colored peeling off bark. The leaves have 5–6 leaflets in the end. It may drop leaves in autumn and winter. The flowers are like

catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in ''Salix''). They contain many, usually unisexual flowers, arranged cl ...

s, rod or bottle-brush-like, white or light yellow in color. The pods are multichambered, and 3–4 in long specimens. The flowers occur in pale yellow spikes.

Distribution and habitat

The plant is endemic to Sonora (

Sonoran desert The Sonoran Desert ( es, Desierto de Sonora) is a desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States (in Arizona ...

. It prefers rocky bajdas,

slope In mathematics, the slope or gradient of a line is a number that describes both the ''direction'' and the ''steepness'' of the line. Slope is often denoted by the letter ''m''; there is no clear answer to the question why the letter ''m'' is use ...

s and

arroyos Arroyo often refers to: * Arroyo (creek), an intermittently dry creek Arroyo may also refer to: People * Arroyo (surname) Places United States ;California * Arroyo Burro Beach, a public beach park in Santa Barbara County, California * Arroyo ...

from 0 to 2,000 feet

elevation The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Vert ...

. It is a popular ornamental tree in arid areas, especially in the southwestern U.S. File:Acacia-willardiana-bark.jpg, The peeling white bark of ''Mariosousa heterophylla'' File:Acacia-willardiana-bark2.jpg

References

* * {{Taxonbar, from=Q4671022 Flora of Mexico heterophylla Flora of the Sonoran Deserts Plants described in 1890