Phytolacca DIOICA

Phytolacca DIOICA - Dioecious pokeweed, Phytolacca dioica, Ombu.

Phytolacca, or pokeweed, is a genus in the pokeweed family (Phytolaccaceae), comprising about two dozen species of herbaceous plants, shrubs, and trees. Most species originate from the Americas and East Asia.

Plants with alternate, long-petioled entire leaves and small apetalous flowers gathered in dense racemose inflorescences. The fruit is a juicy berry, dark in most species.

Dioecious pokeweed differs sharply from its relatives in size: it is the only species in the genus that grows into a true tree. Its native range covers northern Argentina, southern Brazil, Uruguay, Paraguay, and Bolivia, where it grows in subtropical forests, open woodlands, and savannas on low plateaus.

Dioecious pokeweed is an evergreen tree with a massive, often heavily shortened trunk that broadens at the very ground into a wide, gentle cone. The crown is dome-shaped, dense, broad, and low-hanging.

Leaves are dark green, leathery, oval or elliptical, 10-15 cm (4-6 in) long, with pinkish veins. Flowering is very abundant in late spring and early summer, with small yellowish-white flowers in drooping racemes. Male specimens differ from female ones by numerous stamens. The fruits are greenish-yellow flattened berries just under 1 cm (0.4 in) across, ripening by late summer.

Pokeweed seeds are medium-small with a dense coat, so preparation before sowing is mandatory. Seeds are soaked for 24 hours in room-temperature water or in a solution of growth stimulant: SUPERthrive, HB-101, Aminosol, Epin, or Zircon, and then wrapped in a damp cloth for 3-5 days to swell. Scarification and stratification are not required.

Sowing is carried out in spring, in individual pots with a sterile mixture of peat, sand, and humus, to a depth of about 1 cm (0.4 in). The sowing is moistened from a spray bottle, covered with a transparent lid or placed in a greenhouse, and germinated at a temperature of 22-26 °C (72-79 °F).

Sprouts appear in 2-4 weeks; individual seeds may linger longer. Sowings are ventilated daily and condensation is removed. Seedlings grow quickly and already in their first year begin thickening the base of the stem, so they are immediately potted on into deep pots without disturbing the root ball.

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The plant needs bright sunny lighting; in summer it is beneficial to take it outdoors into the open air.

Wintering is possible both warm, from 18 °C (64 °F), and cool, at 12-15 °C (54-59 °F), but always bright. In nature and in open ground in a humid climate, the tree tolerates drops to a few degrees above freezing and brief light frosts.

Watering is abundant during active growth, allowing the top layer of substrate to dry between waterings. During cool wintering, watering is sharply reduced. Higher air humidity is desirable.

The substrate should be nutritious, acidic or slightly acidic, well-drained, based on leaf mold and peat with the addition of sand and perlite. Drainage is mandatory at the bottom of the pot.

Feeding with a complete fertilizer is applied once every two to three weeks from spring to late summer, and is not carried out in winter.

The ombu grows very fast, so the crown is regularly shaped by pruning, and repotting is carried out annually in spring. In open ground, the tree is not planted near buildings: the root system is massive and aggressive.

Special notes: The berries and sap of the plant contain toxic substances and are not edible. When pruning, it is best to work in gloves, and keep the plant out of reach of children and domestic pets.