Yucca brevifolia

Yucca brevifolia

The Joshua Tree or Yucca palm or Yucca tree (Yucca brevifolia Engelm., 1871) is an arboreal species belonging to the Asparagaceae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Plantae,
Superdivision Angiosperms,
Magnoliophyta division,
Class Liliopsida,
Order Liliales,
Agavaceae family,
Genus Yucca,
Species Y. brevifolia.
The terms are synonyms:
– Cleistoyucca arborescens (Torr.) Eastw.;
– Cleistoyucca brevifolia (Engelm.) Rydb.;
– Clistoyucca arborescens (Torr.) Trel.;
– Clistoyucca brevifolia (Engelm.) Rydb.;
– Sarcoyucca brevifolia (Engelm.) Linding.;
– Yucca arborescens (Torr.) Trel.;
– Yucca brevifolia f. herbertii J.M.Webber;
– Yucca brevifolia subsp. herbertii (J.M.Webber) Hochstätter;
– Yucca brevifolia subsp. jaegeriana (McKelvey) Hochstätter;
– Yucca brevifolia var. brevifolia;
– Yucca brevifolia var. herbertii (J.M.Webber) Munz;
– Yucca brevifolia var. jaegeriana McKelvey;
– Yucca draconis var. arborescens Torr.;
– Yucca jaegeriana (McKelvey) L.W.Lenz.

Etymology –
The term Yucca comes from the Spanish yuca or juca, already attested in 1500, in turn from an Amerindian language, probably from Arawak, where however it indicated cassava.
The specific epithet brevifolia comes from the Latin from brévis, short, short and from folium leaf: with short or shorter leaves than those of related species.
The English common name Joshua tree was given by a group of Mormon settlers who crossed the Mojave Desert in the mid-19th century. The particular shape of the tree reminded them of a passage from the Bible in which Moses raised his arms to heaven to pray and only when his arms were raised Joshua and his army won (Exodus 17,8-16).

Geographic Distribution and Habitat –
Yucca brevifolia is a plant endemic to the southwestern United States, distributed with different populations in western Arizona, southeastern California, southern Nevada and southwestern Utah and northern Mexico.
This is an area that coincides with the extension of the Mojave Desert, in which the plant is considered one of the major species indicators for the desert.
Its natural habitat is that of arid heights and mountain slopes, usually at altitudes between 650 and 2,200 meters.

Description –
Yucca brevifolia is a plant that grows in tree conformation with a height of the largest specimens up to 15 m in height.
Usually produces a single trunk, occasionally several; the trunk may be unbranched, especially when young, often becoming multi-branched as it ages.
The leaves are dark green, linear, elongated, 15 to 35 cm long and 7 to 15 mm wide at the base, tapering towards the tip; they are born in dense whorls at the ends of the branches. The outline of the leaves is white and smooth.
Each individual flower is 4–7 cm tall, with six creamy white to green tepals. The tepals are lanceolate and are fused in the middle. The pistils are 3 cm high and the cavity of the stigmas is surrounded by lobes. The flowers of this species are foul smelling.
The flowering period is in spring, from February to April, in glumes 30–55 cm high and 30–38 cm wide.
Y. brevifolia generally does not branch during flowering, and flowering is not annual. In fact, like many desert plants, flowering depends on the rains and needs winter frosts.
The fruit is green-brown, elliptical in shape and contains many flat-shaped seeds.
The fruits are ellipsoid, dry and spongy, and can be 60 – 85 mm long.

Cultivation –
Yucca brevifolia is a plant native to southwestern North America in the states of California, Arizona, Utah and Nevada where it thrives in the open prairies of Queen Valley and Lost Horse Valley, within Joshua Tree National Park.
The plant is harvested from the wild for local use as a food and source of materials. The roots of Yucca species are rich in saponins and have a wide range of applications. The plant is often grown as an ornamental in gardens.
In the areas of origin, which are semi-arid with hot summers and cold winters, in a climate where it survives winter temperatures that go down to -25°C while summer temperatures can reach up to 51°C.
It grows in areas where annual rainfall may be as low as 100mm or 430mm with a summer drought of around 3 months.
For this reason the plant becomes less resistant in more humid climates.
From the pedological point of view, it grows in any soil but prefers a sandy substrate, tolerating alkaline and saline soils and full southern exposure; plants are hardiest when growing on poor sandy soils and a warm, dry location.
The adult plants then become very resistant to drought.
Yucca brevifolia is a slow-growing plant pollinated by moths (Tegeticula yucasella and similar species) with which they have a special plant-insect mutualism.
At night the fragrant flowers attract the female moth which feeds on the nectar. She then rolls the pollen from the flowers into a ball that is three times the size of her head and carries the pollen ball to the next flower. There, she first lays eggs inside the immature ovary and then deposits pollen on the stigma of the flower ensuring that seeds are formed to feed her progeny. Because the larvae mature before they can consume all of the seeds (60 to 80% of the seeds remain viable), the plants are also able to reproduce.
In regions where the moth cannot live and if fruits and seeds are needed, hand pollination is required. This can be done quite easily and successfully using something like a small brush.
The single terminal shoots are monocarpic and die after flowering; however, the stem will usually produce a series of side shoots, which will grow to flower in subsequent years.
Furthermore, plants often survive fire: if the fire is not too hot, the crown of older plants that have lost dead leaves can survive; in hotter fires the plant often grows back from the roots.
In the wild, new plants usually grow from seeds, but in some populations, new stamens grow from the root rhizome found under the tree.
To reproduce the plant, sowing can be done in spring.
Pre-soaking the seed for 24 hours in warm water can shorten the germination time. Generally this germinates within 1 – 12 months when stored at a temperature of 20°C.
The individual seedlings are then placed in individual pots and raised in unheated greenhouses especially in colder climates, at least the first two winters. Transplant should be done in early summer, taking care to give them some winter protection at least for their first winter outdoors; a simple glass plate is usually sufficient.
It can be propagated asexually via root cuttings in late winter or early spring. You need to lift in mid spring and remove the small shoots from the base of the stem and rhizomes. It is then necessary to immerse it in dry wood ash to stop any loss of liquids from the plant and then place it in sandy soil in pots and in a greenhouse until it is stabilized.
Another way to propagate the plant is by dividing the suckers to be done in late spring. Larger divisions can be planted directly in the open field.
Instead it is best to repot the smaller divisions and grow them in light shade in a greenhouse or sheltered area until they grow well and transplant them the following spring.
Specimens of Y. brevifolia grow quickly to be desert plants; new seeds may grow an average of 3 inches per year for the first 10 years, then transition to a growth of 1.5 inches per year. The trunk is made up of hundreds of tiny fibers and the lack of growth circles makes it difficult to determine the tree’s age. This tree has a system of tall thick branches, as well as “deep and extensive” roots, with the roots reaching up to 11m in length.
If it survives the desert climate it can live for hundreds of years.

Customs and Traditions –
Yucca brevifolia is a plant known and used by indigenous American populations since ancient times.
The Cahuilla Native American tribe in the southwestern United States regarded this plant as a valuable resource and called it hunuvat chiy’a or humwichawa. Their ancestors used the leaves of Y. brevifolia to weave sandals and baskets in addition to collecting the seeds and buds for food.
Following the arrival of European colonists, ranchers and miners who were associated with the Mormons obtained benefits from Y. brevifolia, using its trunks and branches for shelter and as fuel for steam vehicles.
The first formal description in the botanical literature as Yucca brevifolia was made in 1871 by George Engelmann, in his Geological Exploration of the Fortieth Parallel.
This plant has such characteristics that it can be used for various uses.
In the food sector, cooked flowers are consumed.
The flower buds, before opening, can be blanched in salted water to eliminate the bitterness, drained and then cooked again and served like cauliflower.
The opened flowers are high in sugar and can be roasted and eaten like candy.
The fruits are eaten cooked. They can be roasted, then made into cakes and dried for later use.
The roots are eaten raw, boiled or roasted.
The seeds are collected and eaten by the local Indians. No further details are given but they are probably ground into a powder and mixed with cornmeal or other flours and used to make breads, sweets etc.
Even the tender pods are said to be eaten.
In the medicinal field, the roots are used which are anti-inflammatory, anti-tumor and antiviral.
The roots of Yucca species are rich in saponins and active medicinal compounds. The roots, harvested when the plant is not in flower, are used to make a healthy drink. It has been shown to lower blood cholesterol and triglyceride levels, lower blood pressure, and reduce osteoarthritis symptoms such as pain, swelling, and stiffness.
These taken orally are used in the treatment of osteoarthritis, hypertension, migraine, colitis, stomach disorders, hypercholesterolemia, diabetes, poor circulation and liver and gallbladder disorders.
Applied topically, they are used to treat sores, skin diseases, inflammation, bleeding, sprains, broken limbs, joint pain, baldness and dandruff.
Many yucca compounds have been used in the synthesis of new drugs.
Among other uses, it should be remembered that a fiber obtained from the leaves is used to make ropes, baskets, sandals, clothes and mats.
The whole leaf can be woven into mats etc. and can also be used as a brush.
The dark red core of the roots was used as material to create patterns in coiled baskets.
The core is divided into threads, wetted and worked with the winding so that the color is always on the outside.
Red and black dyes were obtained from the roots.
The roots which, as mentioned, are rich in saponins can be used as a soap substitute, even for a good hair wash.
The juice of the plant has a wide variety of uses. In agriculture it is used as a base in liquid fertilizers where its ability to reduce the surface tension of irrigation water greatly favors its penetration into heavy soils; markedly favors soil flocculation; serves as a transport agent for plant-food chemicals.
Yucca extract itself is rich in vital minor elements including boron, iron, magnesium, manganese, copper and zinc.
The juice is said to be widely used as a carbon dioxide stabilizer in oil fire control, and the saponin of the yucca is considered a good base for soaps, shampoos, washing powders and toothpastes, and powders.
The wood is light, soft, spongy, difficult to work.
The logs were used in ancient cave dwellings in Arizona. These are sometimes cut into thin layers and used as wrapping material, or packed into boxes and other small items.
From an ecological point of view, the IUCN Red List classifies Yucca brevifolia as a species at least risk (Least Concern).
However, there are some problems in the preservation of Y. brevifolia within the Joshua Tree National Park, due to the climate changes taking place on the planet, which would damage and profoundly transform the ecosystem of the park. There are also concerns about the tree’s natural ability to “migrate” to more favorable climates, due to the extinction of a type of sloth (Nothrotheriops shastensis) which occurred about 13,000 years ago: in fact, in the droppings of these sloth ancestors there are remains of leaves, fruit and seeds of Y. brevifolia were found, suggesting that it played a key role in the spread of trees through the spread of ingested seeds.

Method of Preparation –
Yucca brevifolia is a plant with multiple uses and preparations, both in the food, medicinal and for the extraction of materials.
Both cooked flowers are consumed and can be blanched in salted water to eliminate the bitterness, drained and then cooked again and served like cauliflower.
The opened flowers can be roasted and eaten and the fruits are also eaten cooked, roasted and dried for later use.
The roots are eaten raw, boiled or roasted.
The seeds are collected and eaten by the local Indians.
In the medicinal field, the roots are used, which are harvested when the plant is not in flower, and are used to make a healthy drink.
They are also applied topically to treat sores, skin conditions, and other remedies.
Among other uses, it should be remembered that a fiber obtained from the leaves is used to make ropes, baskets, sandals, clothes and mats.
While other parts of the plant, as mentioned, are used in various materials and types of processing.
Red and black dyes were once obtained from the roots.
The juice of the plant also has a wide variety of uses, including in agriculture.
The logs were used in ancient cave dwellings in Arizona.

Guido Bissanti

Sources
– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Useful Tropical Plants Database.
– Conti F., Abbate G., Alessandrini A., Blasi C. (ed.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora of Italy, Edagricole, Bologna.
– Treben M., 2000. Health from the Lord’s Pharmacy, Advice and experiences with medicinal herbs, Ennsthaler Editore.

Photo source:
– https://inaturalist-open-data.s3.amazonaws.com/photos/253516682/original.jpg

Attention: The pharmaceutical applications and alimurgical uses are indicated for informational purposes only, they do not in any way represent a medical prescription; we therefore decline all responsibility for their use for curative, aesthetic or food purposes.