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Tilt Head aloe (Aloe speciosa 'Tilt Head') is in the far northwestern corner of the Arid Greenhouse.
Tilt Head aloe (Aloe speciosa 'Tilt Head') is a tall, erect, handsome aloe that reaches a height of 9 to nearly 20 feet in height. The serrated leaves are pale bluish-green, often tinged pink at the tips and edges with small, red teeth. Dense cylindrical flower heads of red buds open greenish-white. This species is easy to distinguish, with its head of rosette leaves tilting to catch maximum amount of sunlight.
Each inflorescence is a short, cylindrical raceme (cluster) about 20 inches long, densely packed with flowers. The inflorescence is solitary, but one rosette can produce up to four inflorescences. The peduncle, or stalk, is short, and covered at the base by papery bracts. When the flowers open, the dark orange stamens and style protrude conspicuously from the tips of the flowers.
Tilt Head aloe's flowers are rich in nectar, attracting sunbirds, bees, butterflies, and ants. Aloe speciosa was named in the Journal of the Linnean Society in 1880. The name "speciosa" means "showy" in Latin, and refers to this aloe's striking floral display. Although no medicinal use of this aloe has been recorded, the leaves can be used to dye wool a delicate pink without the need for substances that set the dye on fabric. This plant thrives in sunny locations, in a fertile, sandy loam soil, and once established, it should be self-sustaining.
Clerodendrum quadriloculare, or shooting star, is a stunning subtropical shrub featuring pink-and-white balls of flowers from 6 to 10 inches across in winter. The foliage, to 6 inches in length, is greenish purple on the top of the leaf, and deep purple underneath. A member of Verbenaceae family, molecular data now suggests this genus is really more closely allied with the Lamiaceae, or mint, family. In subtropical climates this plant can reach 10 feet in height and be trained as a large shrub or a single-trunked small tree. If pruned back too hard, the plant responds by sending out root suckers that can be controlled by hand pulling (or by running over them with a lawnmower, as one gardener recommended).
The distribution of this plant is odd, being found in the wilds in Africa and some of the islands in the Pacific — which raises the question of how it got to those two widely dispersed locations without any populations in the intervening countries.
Shooting star (Clerodendrum quadriloculare) is in the south corner of the Semitropical Greenhouse.
Crown of thorns (Euphorbia milii var. splendens) is a slow-growing plant with a rambling growth habit, whose individual plants can grow to 3 feet by 3 feet. Its five- to six-sided fleshy, thorny stems are adorned with short, oblong leaves. The flowers — yellow cyathia enclosed by red bracts — require full sun and moderate temperatures, and low humidity. It's a perfect addition to the desert garden.
The name of this plant is from the Latin euphorbea for Euphorbius, a Greek physician in 1 A.D. who used the sap medicinally. The milky latex sap of this Madagascar native "bleeds" when stems are cut, and can be stopped by immersing in warm water. The Euphorbiaceae are a very large genus, containing more than 2,000 species, including the popular poinsettia.
Crown of thorns (Euphorbia milii var. splendens) is in the Arid Greenhouse.
Roy Tokunaga orchid (Dendrobium Roy Tokunaga) is a cross between Dendrobium johnsoniae and Dendrobium atroviolaceum, and its main feature is an incredibly long bloom time: it begins to flower in November, and continues blooming for close to six months.
This Latouria, or New Guinea-type orchid, is white with dark purple nectar guides. Like most Latouria orchids, Roy Tokunaga requires a brightly lit environment (not direct sunlight) with relatively high humidity, and it must be kept well-watered, but not soggy. This host of requirements can make this particular dendrobium a challenge for Chicago-area homeowners.
Roy Tokunaga orchid (Dendrobium Roy Tokunaga) is on the easternmost orchid tree in the Tropical Greenhouse.
Satin Doll orchid (Brassolaelia Sea Urchin 'Satin Doll') is the darkest cultivar of this primary hybrid of Laelia anceps and Brassovola glauca. It's a very free-flowering plant with an occasional off-season spike. Lightly fragrant, it is temperature-tolerant and begins blooming during November and December. Northern orchid growers particularly appreciate the lower costs associated with keeping this orchid "warm enough" in their greenhouses during Chicago winters.
Satin Doll orchid (Brassolaelia Sea Urchin 'Satin Doll') is on the westernmost orchid tree in the Tropical Greenhouse.