Tree crinum (Crinum asiaticum, L. 1753)

Identity

Tree crinum (Crinum asiaticum L., 1753), also known as giant crinum lily, grand crinum lily, spider lily or poison bulb, is a bulbous perennial in the genus Crinum. It belongs to the Amaryllidaceae rather than the Liliaceae family of true lilies. The genus name comes from Greek krinon, meaning lily, in reference to its large white flowers rather than a close botanical relationship. ^{1 2}

Linnaeus described this species in Species Plantarum in 1753. It later acquired numerous synonyms, including Crinum toxicarium var. asiaticum, a name that points to toxicity recognized long before its current ornamental use. The English name poison bulb preserves that same warning despite its popularity in tropical gardens. ^{2 8}

Recognition

A dense rosette of large, fleshy, arching leaves gives Tree crinum its substantial outline. Established plants have leaves more than 1 m (3.3 ft) long. The bulky bulb is partly visible above ground and extends into a fibrous neck resembling a short trunk. In open ground, the plant reaches 1–1.8 m (3.3–6 ft) including its flower stalk, compared with only 20–40 cm (8–16 in) for a young bulb still developing roots. ^{4 3}

An upright, leafless stalk carries an umbel of 20–30 white flowers, sometimes flushed pale purple. Each flower measures 8–10 cm (3–4 in) across, with long, narrow, recurved tepals that explain the name spider lily. Leaves without a flower stalk do not rule out this species: depending on bulb maturity, the first flowers may take several years to appear. ^{4 3}

Useful taxonomy

Geographic varieties of Crinum asiaticum are recognized by Plants of the World Online rather than treated as separate species. Crinum asiaticum var. japonicum Baker, known as hamayu, is native to Korea and southern Japan. Crinum asiaticum var. sinicum (Roxb. ex Herb.) Baker occurs in southeastern China and Taiwan, often with narrower leaves than the typical form. Crinum asiaticum var. pedunculatum (R.Br.) Fosberg & Sachet, from northern and eastern Australia and New Guinea, carries its umbel on a longer stalk. Distribution and slight differences in leaves or stalks distinguish these varieties, rather than toxicity or horticultural use. ^{1 2}

For all three recognized varieties, the accepted species name remains Crinum asiaticum. The old synonym Bulbine asiatica is no longer accepted by Plants of the World Online. ^{1 2}

Habitat and range

Sandy shores and damp forest edges across the Indo-Pacific form the native habitat of Crinum asiaticum. Its range runs from the Indian Ocean, including India, Sri Lanka and Mauritius, through tropical and subtropical Asia, including southern China, Taiwan and Southeast Asia, to the southwestern Pacific, notably northern Australia and Fiji. ^{1 5}

Ornamental introductions into other warm climates have also led to naturalization in wet areas of Florida and Louisiana. The species is not native there: this more recent presence must be distinguished from its original Indo-Pacific range. ^{6 4}

Along its native coastline, the bulb roots deeply in sand and helps reduce erosion on dunes exposed to wind and salt spray. This tolerance of coastal salt explains its popularity in seaside gardens well beyond its native range. ⁴

Life cycle and reproduction

Warm climates allow the bulb to retain its leaves year-round without a pronounced winter rest. Growth slows only below 18 °C (64 °F), both in pots and in open ground. Summer-to-autumn flowering depends chiefly on bulb maturity and available sunlight rather than the calendar alone. ^{4 3}

Offsets formed around the mother bulb provide the main means of propagation. Dividing these offsets produces a flowering plant faster than sowing. Fresh seeds germinate well, but the bulb often needs several years to reach a size sufficient for its first flowers. ³

Outside the tropics, the bulb can withstand brief frosts down to around -5 °C (23 °F), broadly corresponding to USDA zones 9–11 in the horticultural sources consulted. Below this threshold, leaves blacken; regrowth from the bulb remains possible if it has not frozen deeply. ^{3 4}

Uses and risks

Lycorine- and crinamine-type alkaloids occur throughout Crinum asiaticum, especially in the bulb and sap. Ingestion causes mouth irritation, excessive salivation and vomiting in people, cats and dogs. Contact with the sap alone can also irritate skin. These alkaloids explain the name poison bulb despite the widespread cultivation of the plant as an ornamental. ^{3 8}

Traditional medicine has used the bulb in poultices for rheumatic pain and in decoctions for other external applications. These historical practices do not remove its toxicity when swallowed. More recent research tested Crinum asiaticum extract and isolated lycorine for antioxidant activity in human red blood cells subjected to oxidative stress. Their results were weaker than those of vitamin E used as a reference. ^{3 7}

Varieties, look-alikes and related plants

Cream-white stripes distinguish the horticultural form Variegatum. This is a sales label rather than a separate botanical rank, and its variegation can be unstable between offsets. ⁴

Three plants account for the main identification problems. Hymenocallis littoralis has tepals joined at the base into a distinct cup, whereas those of Crinum asiaticum remain free to the base. Crinum bulbispermum often has flowers striped with a stronger pink. The horticultural hybrid Crinum × amabile has larger, more reddish flowers than the wild form.

The Chinese common name 文殊蘭 literally means “Manjushri’s orchid,” although this species belongs to the Amaryllidaceae rather than the Orchidaceae. It reflects an apparent resemblance rather than a family relationship. In Japan, the local variety is known as hamayu and is the emblematic flower of several coastal towns. ^{8 1}

Main sources

• Plants of the World Online / Kew, Crinum asiaticum L.
• International Plant Names Index, Crinum asiaticum L.
• Plants For A Future, Crinum asiaticum
• Missouri Botanical Garden, Plant Finder, Crinum asiaticum
• USDA-ARS GRIN Global, Crinum asiaticum L. taxonomy detail
• Atlas of Florida Plants, Crinum asiaticum
• PubMed, antioxidant activity of Crinum asiaticum extract and lycorine
• Wikipedia (EN), Crinum asiaticum