Yucca filifera

Yucca filifera, sometimes mistakenly called Yucca australis, forms over time a true small tree with a ramified trunk adorned with stiff leaves gathered in rounded rosettes. This large plant then draws the characteristic silhouette of arborescent yuccas that punctuate the desert landscapes of Mexico. While the foliage of this species is quite classic, its monumental summer flowering, with a trailing and non-upright panicle, allows it to be identified with certainty. The flowers of Yucca filifera resemble large, fully open cream-white tulips and give off a slight lemon scent. Seven years of patience are required to obtain a beautiful specimen in open ground, which is reasonable for this type of plant. Its hardiness (-10 °C (14 °F) in well-drained soil) allows it to be grown inland.

Yucca filifera is a plant of the agave family that should not be confused with Yucca australis, a synonym for Yucca faxoniana, which has broader leaves and grows more slowly. Yucca filifera is endemic to the arid regions of northern and central Mexico, notably the Chihuahua Desert. It thrives at altitudes between 1,000 and 1,500 m (3280 and 4920 ft) in rocky or sandy, well-drained soils. Frosts are occasional, but can drop below -10 °C (14 °F) at times.

Young Yucca filifera plants resemble a rosette of stiff, linear leaves, 2 cm (1 in) wide, with curled filamentous margins, bluish-green in colour, terminated by a sturdy spine. The entire structure measures approximately 90 cm (35 in) in all directions and this vegetation persists throughout winter. After 7 to 8 years, the plant begins to form a trunk, and it grows about 20 cm (8 in) per year under good conditions. The terminal rosette eventually gives rise to a few branches, each carrying a rosette of leaves. Ultimately, this yucca forms a small tree with a chandelier-like silhouette, reaching a height of 10 m (33 ft) and a spread of 4 m (13 ft). The trunks of mature plants have a well-enlarged, swollen base. The fantastic flowering occurs in July-August on mature plants. It takes the form of a large panicle applied along the trunk, sometimes exceeding 2 m (7 ft) in length, directed towards the ground. This spectacular inflorescence carries up to 60 branches, each 70 cm (28 in) long, forming a magnificent panicle. Each branch bears 30 to 50 large, white, star-shaped, slightly fragrant flowers. In Mexico, yucca is pollinated by a nocturnal moth that does not live in Europe. To obtain fruits and seeds, manual pollination will be necessary.

Yucca filifera is an easy-going exotic plant in a rather dry climate and well-drained, but deep soil (it has a developed root system). It is adapted to arid situations and tolerates dry cold well. It is advisable to keep it away from walkways and young children due to its pointed leaves. This plant is perfect for structuring a large rock garden or for brilliantly occupying the centre of an exotic bed. It can be planted alone or associated with Puya, Agave americana, prickly pear cacti, Beschorneria, and other hardy candelabra cacti (Cleistocactus strausii, Cylindropuntia imbricata), all equally undemanding. Cultivating it in pots is quite disappointing as it does not allow this yucca to reach its full potential.