In the Fullerton Arboretum

by: Alfredo Chiri

LÚCUMA – Pouteria lucuma – Sapotaceae

Lúcuma de seda’ donated by: CRFG/Silver and planted in 1985 (r.f.-08)

Lúcuma de palo’ donated by: Alfredo Chiri and planted in 1998(r.f.-08)

Common names: (Lúcuma de seda) Lúcuma verde, Rujma, Lúcuma, Lucma. (Lúcuma

de palo) Lúcuma amarilla,Rucma Lúcuma, mamón.

Lúcuma de seda’ and the Lúcuma de palo’ are the most popular varieties among Peruvian natives. De seda has a high content of water and is eaten fresh, while the de palo’ is dryer and is used primarily to make ice cream.

The Lúcuma de palo fruit is yellow in color and appears to have originated in the Peru-vian coastal valleys at the base of the Andes hillsides. The golden color of the fruit is unique to this Peruvian native tree. There are very few cultivars left in Perú that contain this golden charac-teristic, and they are carefully cared for and guarded by a small, select group of Inca descendants. These Inca descendants still consider this fruit to be an important part of their belief in Sun worship, and they believe that the fruit captures the sun's rays at the time of sunrise. The Spanish, during the Inca conquest, believed that the Indians had found a fruit that contained gold, and the ingestion of the fruit would allow them to carry the gold within their bodies to a distant and secret place, which the Spaniards called "El Dorado."

The Lúcuma de seda fruit is green in color and has a bright orange to yellow, dry, mealy pulp. This species is native to the highlands of southern Perú and Bolivia. The tree is an evergreen with a straight trunk, up to 30 cm in diameter. The bark is light brown, thick and rough. This attractive

tree ranges from 25 to 50 ft. (8-15 m) in height, has a dense, rounded crown with drooping branches, and copious milky latex. Growth is slow and resistant to wind and salt air.

The evergreen leaves, clus-tered at the tips of small branches, are obovate, the tips reaching 2 m from the trunk. Before it flowers, many of the previous year¹s leaves are shed to make room for new growth. The leaves are alternate, dark green at the margin.

The flowers are unscented, borne singly in the leaf axil or leaf scars with 5 greenish sepals, ovate, outer densely hairy with rusty hairs and 5 whitish petals, fused below to more than half way, forming a barrel-shaped tube.

The fruit is oblate, from 6 to 7.5 cm long, 6.5 cm in diameter, weighing between 90 to 160 grams, with thin, delicate skin. The smooth skin is marked at the base by a persistent calyx and toward the apex by a ring of wrinkled tissue. The fruit at the early stages is green, turning to a brownish green. Then as the Lúcuma de palo fruit matures, it becomes bright yellow with an orange tint aging to a dark reddish brown. The Lúcuma de seda stays green with a reddish brown tint. The mealy pulp is bright yellow, firm, dry-to-juicy, very sweet with the flavor of an apricot mango combination. The fruit has one seed that is rounded or broad-oval, glossy, dark brown color with a whitish hilum on one flattish side. The seed is contained in a separate loculi. The ball-like endosperm separates easily into two uneven, convex cotyledons.

Mature trees withstand temperatures between 40°F. - 100°F., and prefer open yard sun. Its climatic requirements are roughly comparable to those of lemons. The tree will grow in a wide range of soils and will grow well in areas subjected to occasional dry-ness. It tolerates seasonal rains well, but not water logging. The tree best adapts to sandy or rocky sites and needs well-drained soils. It tolerates moderate salinity, however it thrives in soils high in organic matter.

If temperatures are predicted below 40°F, cover with a blanket if the plants are small (under 2 feet). Otherwise they can survive short frosts. Some burning at the tips would appear during the cold winters, but that is normal. The leaves will be replaced with new ones.

No serious diseases are known to be of sufficient importance to require control measures. Trees are very resistant to pests and diseases in the adult stage. Snails and grasshoppers are "nippers" of the leaves in young trees, but as they grow older, the rich latex will discourage them. Heading-back should be used primarily to promote lower branch growth. Trees should be limited to no more than 3 main branches from the base trunk. Remove all secondary branches below 2 feet. Water at least twice a week in sandy soils, weekly in rocky and loamy soils.

Germination will start about 30 to 60 days after sowing fresh seed. In about one month the seedling attains a height between 3 to 6 inches, which suggests relative slow propa-gation. Although growth is slow, the lúcuma is reputed to start producing in 6 to 10 years. Experiments in grafting and seed grafting are ongoing in Perú, but data is not available at this time.

High temperature (100°F+) during harvest time will precipitate dropping of the fruit. High hot winds will burn the leaves' margins on the wind side but will do no damage to the tree. The fruit falls to the ground shortly before fully ripe. It is advisable to pick the fruits to avoid damage. Such care allows the fruit to be stored for up to 10 days.

To date, the flavor of the lúcuma has not been chemically synthesized, thus creating a plus for new cultivars. The high quality of the fruits will depend on the knowledge of pollination agents and process and all details of its cultivation.

Alfredo Chiri

Centro de Technologia Andina

[email protected]

Home of the 'Inca Gold' Lucuma