Watsonia strictiflora Ker Gawl.
Common names: Klipheuwel watsonia (Eng.); Klipheuwel lakpypie (Afr.)
Watsonia strictiflora is a striking, rose-pink-flowered, dwarf species with peculiar perianth tubes that are straight and constricted below and strongly curved in the upper part. Although critically endangered in the wild, it responds well to cultivation.
This deciduous, winter-growing geophyte grows 240–430 mm high from a rounded corm 20–32 mm in diameter and is covered with layers of tough, brown, netted outer tunics. It produces an erect fan of 5–7, lance-shaped, bright green, flat or slightly spirally twisted leaves, sometimes with reddish margins. The inflorescence is an erect spike bearing 2–11, widely funnel-shaped, bright pink flowers with a narrowly triangular, deep reddish maroon marking at the base of each tepal. Each flower emerges between two bracts and has a long perianth tube 20–36 mm long, which is very straight and constricted (narrowed) in the lower part and strongly curved above, and contains nectar in its base. The three stamens are bent downwards and have prominent anthers 9–11 mm long, with purple pollen. The ripe, reddish brown, oblong seed capsule becomes woody as it matures and the oblong seeds are winged at both ends. The plant flowers from late spring to early summer (mid-October to early December) and is dormant in summer.
According to the Red List of South African Plants, Watsonia strictiflora is assessed as Critically Endangered (CR), due to massive habitat loss from expanding wheat fields, grape plantations and urban sprawl, and to smothering alien vegetation. It has probably always had a limited distribution and unfortunately the surviving subpopulations occur on privately-owned land, not within the boundaries of formal nature reserves. Seeds of W. strictiflora obtained from hand-pollinated plants in the bulb nursery at Kirstenbosch National Botanical Garden, have been collected for long-term storage in the Millenium Seed Bank at Wakehurst Place in the United Kingdom.
Distribution and habitat
Watsonia strictiflora is a narrow endemic of flats and hillsides in the vicinity of Durbanville, east of Cape Town, occurring in Swartland Shale Renosterveld on flats and gentle north-facing slopes, in stony clay. They grow as scattered, solitary individuals or in small groups of up to 7 plants, exposed, or within the protection of low bushy scrub including Eriocephalus africanus (wild rosemary) and Muraltia heisteria (purple gorse), in association with geophytes such as Tritonia undulata and Wachendorfia paniculata (rooikanol). The corms are fairly deep-seated and always wedged between shale stones and rocks. The species is suited to cultivation in frost-free parts of the Western and Northern Cape, which experience winter rainfall and dry summers.
Derivation of name and historical aspects
The Scottish botanist Philip Miller (1691–1771), established the genus Watsonia in 1758 in tribute to the English naturalist and physician, Sir William Watson (1715–1787). W. meriana from the Western Cape became the first species to be illustrated and introduced into cultivation under glass in England and Europe. W. strictiflora was first grown in England by the Rev. William Herbert, probably at his home in Mitcham, Surrey, however, it is unknown who first collected the plant in the wild and from what source the collection was made. Herbert provided a flowering specimen to the botanical artist Sydenham Edwards, who completed an illustration in watercolour and pencil, which accompanied the original text by the English botanist J.B. Ker Gawler, in volume 34 of Curtis’s Botanical Magazine, in 1811. The plant was first cultivated in South Africa in 1979, when specimens collected by the present author were grown in the bulb nursery at Kirstenbosch. The specific name strictiflora is descriptive of the very straight and constricted lower part of the perianth tube. W. strictiflora is similar to W. dubia, another dwarf species from the southwestern Cape, which flowers concurrently, the latter differing in having salmon-pink flowers with a shorter perianth tube, longer filaments and much longer bracts, which become irregularly divided after flowering.
Comprising 52 winter-growing, summer-growing and evergreen species, Watsonia is endemic to South Africa, Lesotho and Swaziland and its centre of diversity is in the southwestern part of the Western Cape. Among the most well known garden subjects are the robust, bright pink W. borbonica subsp. borbonica, the pure white W. borbonica subsp. ardernei, the red, orange or shell-pink W. meriana var. meriana and the scarlet W. angusta, though most watsonias in general garden cultivation are of hybrid origin, most of which have W. meriana in their ancestry. Several species have become naturalized in temperate parts, notably the robust W. meriana var. bulbillifera, which forms copious cormlets in the axils of the flower stems, resulting in dense stands in seasonally wet sites; it has become a rampant weed in southwestern, southern and eastern Australia and in Tasmania, as well as in New Zealand and California. The genus includes dwarf species such as W. minima, as short as 100 mm high in flower, and the giant W. vanderspuyiae and W. meriana var. bulbillifera which can grow to 2 m or more.
Watsonia strictiflora is a deciduous, winter-growing plant adapted to mild, moist winters and hot, dry summers. Flowering takes place in late spring and early summer at the end of the growing season and the corms are completely dormant in summer. During the course of each growing season, a new corm develops directly above the old corm, the latter withering completely by early summer. The corms are fairly deep-seated and always securely wedged between shale stones and rocks, an adaptive strategy to evade excavation by Cape porcupines. Nevertheless, these persistent rodents do sometimes manage to excavate some of the corms. The flowers are pollinated by long-proboscid flies, attracted by a narrowly triangular, deep reddish maroon marking at the base of each tepal. The fly hovers briefly in front of the flowers, inserts the proboscis for a few seconds, sucks up nectar, withdraws and flies off. Black-and-yellow Lunate blister beetles cause considerable damage in consuming the tepals, but may be effective in transferring pollen on their wing covers. The leaves, flowers and stems are often grazed almost to the ground by wild antelope, thus severely limiting seed production.
This species has no traditional, economic or magical uses.
Growing Watsonia strictiflora
W. strictiflora is recommended for 25–30 cm diameter plastic pots, and to dedicated rock garden pockets. It is best suited to frost-free conditions, but can probably take light frost for short periods of a few hours. Although it occurs in stony clay soils in the wild, it readily adapts to well-drained, sandy media in cultivation. A suggested mixture is equal parts of coarse silica sand and finely sifted compost, with the addition of a 5 cm layer of compost, placed in the base of the pot. Plant the corms in a position receiving full sun in autumn, about 3 cm deep, and give an initial heavy watering. Once the leaf shoots appear, water heavily about twice per week throughout the winter months. Because this species flowers at the end of the growing season, it is important that the plants are kept well watered throughout spring and early summer, in order for the developing flower spikes to remain strong and not abort. Once the leaves begin to turn brown, withhold watering completely for the duration of summer. In temperate climates where porcupines and molerats are not prevalent, W. strictiflora can also be grown in rock garden pockets, provided the soil is kept absolutely dry in summer. In ideal conditions, the plants can grow considerably taller than those in the wild, reaching up to 770 mm high in flower.
When grown in enclosed conditions such as in hothouses, the developing flower buds are susceptible to infestation by thrips just prior to flowering in late spring and early summer, coinciding with rising temperature, causing severe malformation, and need to be treated while in early bud stage. The corms are not susceptible to mealy bug infestation, but the leaves are subject to attack by red spider mites, in late spring and early summer. The corms do not readily produce offsets and propagation is best from seed. Hand-pollination and isolation from other species of Watsonia and hybrids, is essential to obtain pure seeds that will flower true-to-type. Sow the seeds 3–5 mm deep in autumn, in deep seed trays, pots or bulb beds, in the same medium recommended for adult corms. If sown fresh, seeds will germinate within 3 weeks. Feeding with fertilizer of seaweed extract is beneficial in advancing corm development. Allow seedlings to remain in the same position for 2 years, and pot-up into nursery bags or permanent pots at the beginning of the third autumn. In ideal conditions, seedlings can be expected to flower in the third or fourth year.
- Duncan, G.D. 2002. Dwarf watsonias, ten of the best for containers and rock gardens. Veld & Flora 88(3): 94–98.
- Duncan, G. 2010. Grow bulbs. Kirstenbosch Gardening Series. South African National Biodiversity Institute, Cape Town.
- Duncan, G.D. 2015. Watsonia strictiflora. Curtis’s Botanical Magazine 32: 116–125.
- Goldblatt, P. 1989. The genus Watsonia. Annals of Kirstenbosch Botanic Gardens Vol. 19. National Botanic Gardens, Kirstenbosch.
- iSpot southern Africa: ispotnature.org/species-dictionaries/sanbi/Watsonia%20strictiflora
- Ker Gawler, J.B. 1811. Watsonia strictiflora. Curtis’s Botanical Magazine 34: t. 1406.
Kirstenbosch National Botanical Garden
Plant Type: Bulb
SA Distribution: Western Cape
Soil type: Sandy, Clay
Flowering season: Spring, Early Summer
PH: Acid, Neutral
Flower colour: Pink
Aspect: Full Sun
Gardening skill: Average