Origin and Habitat: Angola, South Africa and Swaziland
Altitude range: 33 ft - 4,920 ft (10-1500 m) above sea level.
Habitat and ecology:Euphorbia ingens is common from low to higher altitudes, usually solitary, in dry bushveld, often on rocky outcrops on steep rocky hillsides on deep sand in wooded grassland, also on termitaria.
Description:Euphorbia ingens (Giant euphorbia) is a spiny, succulent medium-sized to large trees 4–12(15) m tall, with a sturdy main stem and a massive dark green crown branching in a broadly obconical manner or in the shape of an over-sized egg-cup and not distinctly candelabra-like. Euphorbia ingens is very similar to Euphorbia candelabrum from the Horn of Africa and eastern Africa, and may be conspecific. The branches of Euphorbia ingens are usually more distinctly and shortly segmented, the teeth along the angles are usually further apart and the branch tips bear fewer inflorescences.
Stem: Trunk stout simple; bark rough fissured grey. Branches robust, about 3 m upwards, erect or ascending, rebranching, high succulent, leafless, usually 4- or 5-angled, straight, subparallel, all attaining to about the same general level, with parallel sides. Lower branches not shed with age as in many other species. Flowering branches 4-angled, usually constricted at irregular intervals into oblong segments 7-15 (or more) cm long , 5-7.5 (12) in cm diameter, square in cross-section to distinctly but stoutly winged. Angles wing-like, 5-6 mm thick at the obscurely crenate or sinuate margin, 2-3 cm broad, bearing shallow tubercles 1–2 cm apart deep green.
Leaves: Rudimentary and scale-like, 2-3 mm long, obovate or broadly ovate, acute, with a hard rigid dark brown auricle (stipule) on each side at the base, glabrous, soon deciduous.
Spines: Spineless or with a pair of reduced spines 0.5-2 mm long borne on separate Spine-shields that do not form a continuous ridge. Spine-shields 12-18 mm apart, 4-5 mm in diameter, suborbicular or transversely elliptic or reniform, usually poorly developed and formed of a thin rust-colored disintegrating substance.
Inflorescences: Born in profusion along the margins at stem tips on flowering-eyes nearly or quite contiguous to the spine-shields. Each flowering-eye with 3 cymes on stout peduncles 2-3 mm long, bearing 3 cyathia, all at first sessile, the lateral ultimately on very short branches. Bracts 3-5 mm long, 4-6 mm broad, very broadly rounded, obtuse or subacute, concave, glabrous.
Flowers (cyathia): Very small greenish yellow to bright yellow 8-10 mm in diameter, cup-shaped or somewhat obconic, glabrous outside, with 5 glands and 5 transversely oblong or subquadrate fringed lobes. Glands contiguous, 3-5 mm in their greater diameter, somewhat half circular in outline when seen from above, and from beneath somewhat triangular with rounded auricles at the base, thick and fleshy, with a sharp ridge along their inner margin, thence sloping to the acute edge of the outer margin, smooth, light green. Perianth irregularly divided into 3 or more filiform lobes 2–4 mm long, sometimes with 1 or 2 teeth.
*Female flower: Styles 3 (rarely 2), 3–3.5 mm long, joined for 1.5 mm, apices thickened, rugulose, bifid. Ovary at first subsessile, with a conspicuous 3-lobed calyx at its base, becoming exerted in young fruit on a stout pedicel as long as the cyathium, glabrous.
Male flowers: Many, bracteoles spathulate, plumose; stamens c. 5.5 mm long.
Fruit (capsules): Shortly exerted on a stout pedicel 5 mm long, (2)3-locular, almost globose, erect, 7-10 mm in diameter, green becoming reddish, with the outer substance evidently somewhat fleshy, glabrous, hardening immediately before dehiscence to 6 × 9 mm, and very obtusely (2)3-lobed.
Seeds: 3-4 mm long, subglobose to ellipsoid, slightly compressed laterally,, with a slight groove down the ventral side, and a slight keel down the dorsal, very faintly and minutely tuberculate as seen under a lens, greyish-brown speckled with paler brown, smooth.
Cultivation and Propagation: Euphorbia ingens is an easy species to grow that is suited for any well drained soil in full sun. But young plant are happy growing indoors, where they can easily reach the ceiling.
Growing rate: It is a moderately fast grower, and will quickly become large landscape masterpieces in just 3-5 years.
Soil and pots: Give the plant an airy growing medium which mainly consists of non organic material such as clay, pumice, lava grit, and only a little peat or leaf-mould. If plant becomes very red, this is a sign that the roots have not developed properly, so repot the plant with fresh growing medium. Like quite small pots, repot in very later winter, early spring. It will be content in its position and with its soil for years.
Watering: Water regularly during the active growing season from March to September. No water should ever be allowed to stand around the roots. Keep almost completely dry in winter.
Fertilization: Need a perfect fertilizer diet in summer. Use preferably a cacti and succulents fertilizer with high potassium content including all micronutrients and trace elements or slow release fertilizer.
Wing tolerance: Only downside is from strong winds, the columns often smash into each other, causing permanent scarring... best to plant in such a location where winds are not a big issue.
Exposure: It can tolerate moderate shade, and a plant that has been growing in shade should be slowly hardened off before placing it in full sun as the plant will be severely scorched if moved too suddenly from shade into sun.
Maintenance: Can be pruned for shape and branching.
Hardiness: Frost tender, frost free zones only. Severe frost is sure to damage or even kill mature and established plants of Euphorbia ingens.
Warning: All Euphorbias contain a white sap that can be irritating to eyes and mucous membranes. If contact is made with this white sap, take care to not touch face or eyes before washing hands with soap and water.
Gardening: This tree can be grown in large, rocky, well-drained soil in gardens in drier areas. It is very drought resistant but susceptible to frost. It makes one of the better house plants for an Euphorbia, dealing well with low light situations (though recommend higher light if possible). Somewhat user-friendly with only sparse spines along the edges of the plant. Slightly delicate, though, and spines tear off easily, exposing that latexy sap. It is also appreciated as a live fence because it is easily propagated from untreated mature branch cuttings.
Traditional uses: In Zimbabwe, the latex of this species was burned to produce smoke that was inhaled for the treatment of asthma and bronchitis
Propagation: It is easy to propagate by cuttings in late spring to summer, just take a cutting of the plant let it dry for 1 or 2 weeks and stuff it in the ground (preferably dry, loose, extremely well draining soil). It is better to wash the cut to remove the latex. Place the cutting in a warm, bright and slightly humid spot, to increase the building of new roots.
"Euphorbia ingens" Text available under a CC-BY-SA Creative Commons Attribution License. www.llifle.com 14 Nov. 2005. 07 Mar 2021. </Encyclopedia/SUCCULENTS/Family/Euphorbiaceae/27231/Euphorbia_ingens>