This species has often been treated as a subspecies or variety of Dioon edule. It is treated here as distinct as per Osborne, R., Calonje, M.A., Hill, K.D., Stanberg, L. & Stevenson, D.W. (2012). The world list of Cycads Memoirs of the New York Botanical Garden 106: 480-510.
The uses of this plant are the same as for Dioon edule[].

Common Name:

General Information

Dioon angustifolium is a slow-growing, evergreen, palm-like plant with an erect to decumbent, unbranched main stem that can eventually be up to 2.5 metres tall and 20 - 40cm in diameter; this is topped by a crown of numerous large leaves each around 90 - 140cm long[].
The edible seed is gathered from the wild and used locally. There is a long history of the use of this plant as a food in Mexico - in the past it was often used as a staple food, though now it is more likely to be used only in times of food shortage.
The population of Dioon angustifolium has declined by 10 - 30% in different subpopulations over the past 50 years, and there is an estimated ongoing decline of at least 20% over the next generation. The plant is classified as 'Vulnerable' in the IUCN Red List of Threatened Species(2010)[].

Known Hazards

None known

Botanical References

Range

Southern N. America - northeastern Mexico (Nuevo León, Tamaulipas).

Habitat

Among rocks and on slopes in drier types of deciduous forest and shrubland[]. Generally in areas transitional between tropical deciduous forest and oak woodland, growing in rocky habitats or on steep cliffs; at elevations from 500 - 1,500 metres[].

Properties

Conservation Status	Vulnerable
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	2.00 m
Growth Rate	Slow
Pollinators	Weevils
Self-fertile	No
Cultivation Status	Ornamental, Wild

Cultivation Details

Dioon angustifolium is found in the subtropical climate of northeastern Mexico, where it is found at elevations up to 1,500 metres. Annual rainfall averages 1,000 - 1,500mm, falling mainly in the summer[]. Dioon species are often frost tolerant to several degrees below freezing, but lower temperatures will cause foliar damage or complete defoliation. High temperatures and full sun do not usually cause damage, even to forest-dwelling species[].
Most species of Dioon are easily cultivated and grow with minimal care[]. This species prefers a position in full sun, but is tolerant of some shade[]. Requires a well-drained soil[]. Plants are able to grow in low light intensities and on poor soils[].
The stems of Dioon species are clothed in a thick armour of old leaf bases that protect them from the frequent fires that pass through their habitat. Their trunks are also clothed in a thick layer of dense, wooly hairs which persist and give protection until burned off[].
Species in this genus form structures known as coralloid roots. These roots branch off from the taproot or secondary roots and are distinctive in that they grow laterally or upward, forming a nodular mass at the apex. These coralloid roots occur slightly below or slightly above the soil surface and generally contain cyanobacteria, also known as blue-green algae. These are able to fix atmospheric nitrogen and make it available as a nutrient to the plant. The ability to extract this important nutrient from the air explains how many cycad species are able to survive on almost sterile soils[].
A dioecious species, with individual plants producing either all male or all female cones. Therefore both male and female forms of the plant need to be grown if seed is required[].
Female plants only produce one seed cone at each reproductive cycle, which generally occurs once every three to four years. This cone take around 8 - 9 months to mature[]. The ovoid cones of this species are 25 - 29cm long and 19 - 24cm in diameter, covered with a dense layer of short woolly hairs[].

Edible Uses

The starch-rich seed can be eaten boiled or roasted[, , ]. A starch can be extracted from the seed - called Mexican arrowroot, it is used in making tortillas[]. The ovoid to subglobose seed is around 19 - 25mm long and 19 - 20mm in diameter[],

Medicinal

A decoction of the seeds is used to treat neuralgia[, ].

Other Uses

A gum can be obtained from the petiole[]. No more details.

Propagation

Seed - it can take about 6 - 8 months to form the embryo after the seed is shed from the cone, but after that germination is usually rapid. Surface sow on damp sand at a temperature of 24 - 32°c[]. On emergence of the radicle, pot the seedling into its own pot of a sandy compost and grow on in shaded warm conditions[]. Avoid any damage to the taproot and coralloid roots when repotting. Repot and feed frequently to encourage development and plant out when whorls of leaves are being produced, which can be 4 - 8 years[]. Seed can store for at least three years withoout noticeable lost of viability[].

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