Mimetes hirtus
Introduction
Sima Eliovson, author of Proteas for pleasure, referred to Mimetes hirtus as 'the most magnificent species of Mimetes, the most spectacular genus of the protea family'. Nevertheless, the future of the species is uncertain as it is also one of the most geographically restricted mimetes, growing only in boggy areas mainly at low altitudes. As a consequence of the latter, it is often out-competed for its preferred habitat by housing developments. Fortunately it is one of the less troublesome to grow in cultivation-an aspect that may aid its chance of survival as a species.
Description
Description
Mimetes hirtus is a single-stemmed, erect, much-branched shrub, 1.0-2.5 m in height with smooth, reddish bark. The branches possess numerous upwardly overlapping, lanceolate leaves, 25-45 x 5-18 mm, that hide the stem almost completely. The leaves and stem are covered in tiny hairs, and the leaf edges are ciliate.
The headlets or groups of flowers are borne in the axils of the uppermost foliage leaves of a flowering branch. There are nine to fourteen flowers in the headlet; each of these being surrounded by bright yellow, tube-shaped bracts with red tips, from which the 50-55 mm long red styles, needle-shaped pollen presenter and fluffy white perianth extend. This composition is known as a 'brush type pseudanthium' and is the least specialized of the flower types of Mimetes.
The inconspicuous green leaf that subtends the flower does not change shape or colour during the flowering period (as is the case in the more advanced mimetes flower types). The tips of the flowering branches are crowned by a flattened crest of soft, rusty brown leaves without flowers in their axils, hence the common name, pineapple bush.
Flowering takes place mainly in winter, in July and August, although it can occur anytime between May and November.
M. hirtus is a relatively short-lived member of the protea family. It grows rapidly as a result, and may start flowering after only two years of growth. Plants reach their peak by ten years of age and die shortly thereafter, at a maximum age of about fifteen years. Fruits are generally ripe within five months following pollination, a rate faster than other species in the genus.
Conservation Status
Status
The species is well conserved at the Cape of Good Hope Nature Reserve that forms part of the Table Mountain National Park, and in the Kogelberg Biosphere Reserve. The population in the Kleinmond Nature Reserve requires monitoring as it may be at risk from the effects of eutrophication. It has been assigned a lower Red Data List status than many of the other species in the genus, but Rourke (1982) considers it to be the most seriously threatened. Strict criteria give it a status of Vulnerable owing mainly to its low-lying areas of occurrence that often clash with urbanization and agricultural development (orchards and pastures). It cannot be termed Endangered as most of its habitat loss occurred over three generations ago. Other major threats include alien invasive plants, wetland drainage and groundwater extraction as well as golf courses, afforestation and eutrophication. Since it is sought after as a cut flower, wild flower harvesting is an added threat. Alien invasive ants pose a problem, as they do not aid seed dispersal, a process in which indigenous ants play a vital role in Mimetes.
Distribution and habitat
Distribution description
Mimetes hirtus is endemic to the winter rainfall Cape Floral Region where it favours seeps and bogs in coastal lowlands and coastal mountain slopes (0-400 m). Seven populations remain in the Cape Peninsula and Houwhoek Centres of Endemism, where it is found in particular abundance at Cape Point and in Betty's Bay. It is extinct in the present-day southern suburbs of the City of Cape Town : Rondebosch (last record 1800), Klaasenbosch (last record 1884) and Wynberg (last record unknown) and presumed extinct in Hermanus and Elim. These losses can possibly be attributed to its habitat preference. Dense local stands usually occur on Table Mountain Sandstone in areas where it obtains groundwater inflow from surrounding slopes, also known as Erica-Osmitopsis Seepage Fynbos (Boucher 1978). It is thus ensured a high soil moisture level, even in the dry summers when the black, peaty, acid fynbos soils retain their moisture and remain damp.
Derivation of name and historical aspects
History
The first written record of Mimetes hirtus dates back to 1672, when Paul Hermann of the Dutch East India Company visited Cape Town . His notes on two species describe plant features that can only be attributed to M. hirtus and M. cucullatus . In 1720, Herman Boerhaave's collection of engravings was published. An illustration of M. hirtus featured here in the group named Hypophyllocarpodendron (tree with fruits under the leaves). The botanical accuracy of the engravings may be questionable, but Boerhaave's habitat description 'in marshes, damp places and indeed, in water itself, grows this five to six foot tree of Africa' confirms the species to be M. hirtus . Carl Linnaeus described and named the plant in 1760 after he received a herbarium specimen as a gift. He named the plant Leucadendron hirtum , the specific epithet meaning hairy, after its hairy stems, possibly because the only other species of the genus described at the time was the hairless M. cucullatus (then called Leucadendron cucullatum ).
R.A. Salisbury established Mimetes as a genus in 1807 after subdividing Linnaeus's genus Leucadendron. The name was derived from a Greek word meaning imitator, copyist, or one who represents characters i.e. an actor or dancer. Since men played the roles of both males and females on the Greek stage, the word was assigned a masculine gender, and Salisbury gave masculine endings to the species he described. Following this, Brown in 1810 and the authors of Flora capensis in 1912 interpreted Mimetes as feminine, hence the name Mimetes hirta can be found in old literature. It is now considered correct to revert to the masculine endings initially assigned and so the name Mimetes hirtus prevails once again.
Mimetes hirtus is one of thirteen species in the genus and is grouped together with the other tube pagodas, M. pauciflorus, M. palustris and M. capitulatus . The brightly coloured, tube-shaped bracts surrounding the flowers and the lack of display function of the leaf subtending the flower, distinguish these from the other Mimetes species.
All species in the genus Mimetes are endemic to the Cape Floral Region and at present only three of these are not threatened with extinction. Of particular interest is the silver pagoda, M. stokoei, which was thought to be extinct after the last remaining plant of the population was killed in 1969. However, after lying dormant underground for approximately three fire cycles, its seeds exhibited remarkable longevity and germinated in 2001, following a suitable fire in 1999.
Ecology
Ecology
All members of the genus Mimetes have evolved flowerheads adapted to pollination by birds. The brightly coloured bracts and styles in shades of red and yellow that are visually attractive to birds, and the diurnal production of large quantities of nectar, provide evidence for this. Sunbirds appear to be the primary pollinators of most Mimetes, while the Cape Sugarbird (Promerops cafer) only visits some species. Conversely, in the case of M. hirtus , the Cape Sugarbird has been proven to be the major pollinator of populations at Betty's Bay, while the Orange-Breasted Sunbird ( Nectarinia violacea ) seems to play a less important role in effecting pollination. These findings could be attributed to the foraging behaviour of the birds as well as the territorial nature of Promerops cafer . The latter was observed foraging on the axillary flowers while perched above the flowerhead. In doing so, the bird reaches down over the stigmata and pollen presenters and brushes its head and throat against them. The Orange-Breasted Sunbird was seen foraging from below or next to the flowers and rarely brushed against the styles or pollen presenters while probing the flowers with its beak. The Cape Sugarbird also exhibited a preference for partially opened flowers as these flowers provide the greatest nectar rewards. Of significance to the plant is the increased likelihood of the bird collecting viable pollen from flowers that are at an early stage of development, as availability of viable pollen on the presenters is greatest at this time. The only invertebrates noted were hemipterans, and they rarely moved onto the styles (Collins 1982). It is unlikely that invertebrates play a deliberate role in pollination.
Invertebrates are essential to the survival of the species, however, as indigenous ants (particularly Anoplolepis custodiens) have a symbiotic association with the plants through which they play a vital role in seed dispersal. The single-seeded fruit of Mimetes hirtus possesses a hard, greyish seed coat surrounded by a soft coating derived from the wall of the ovary. Fleshy thickenings may be observed at both ends of the fruit and these, together with the soft outer coating, function as an elaiosome (strictly speaking an elaiosome is a term given to a chemically attractive appendage of a seed and since Mimetes produces single-seeded fruit, the fleshy parts cannot be called an elaiosome). When the fruits are released, they fall to the ground, and within a few hours the membranous outer layer or pericarp dries. This time constraint does not pose a problem for the ants, however, as they detect the fruit within minutes and quickly alert the rest of the colony, from which assistance is required to drag it into the nest underground. The ants then eat off the fleshy parts and leave the remaining fruit. In doing so, the ants disperse the fruit away from the parent plant and protect it from predators, i.e. birds and rodents, and fire.
Mimetes hirtus forms part of fynbos, a fire-adapted flora. The adult plants are reseeders and hence unable to resprout from a rootstock. As such, they are killed by fire, and the survival of their fruit is essential for survival of the species (hence the importance of the role of the ants). The fruit are able to live for long periods of time underground and germinate after fire, when they are triggered by various cues such as changes in temperature, pH and oxygen levels in the ants' nest.
Since the species exhibits early flowering and senescence, it necessitates being burnt every 15 years, although it can also survive more frequent fires, depending on whether sufficient time is allowed for seedlings that germinated following the previous fire to flower and set seed.
Growing Mimetes hirtus
Grow
Mimetes hirtus has been grown fairly successfully in cultivation, although it does have specific requirements. Since it is a marsh-growing species, it needs extra water and thus prefers areas with high soil moisture content but that still permit free drainage to ensure aeration of the roots. These conditions are not easy to simulate and the position of planting thus requires careful consideration.
Propagation and cultivation
The plants can be propagated from seeds, although given that these are difficult to acquire, propagation by means of cuttings is the preferred method. Cuttings should be either stem tip cuttings or side shoots taken as heel cuttings. The latter are cuttings taken where a side shoot or short twig is pulled off the main stem in such a way that part of the main stem comes off along with the cutting, hereby giving the appearance of a heel.
The cutting material must be 100-120 mm long, approximately as thick as a pencil, and should be young but not too soft. Apply the 'little finger test' i.e. material should resist when one attempts to bend it with one's little finger. A good time to take cuttings is February/March when the new shoots have emerged and hardened off but before buds have formed for winter flowers. The cuttings must be kept cool after harvesting and it is advisable to keep them in a refrigerator for up to two days before setting. Cuttings must be treated with a rooting hormone prior to setting in a rooting medium of 50:50 milled pine bark with polystyrene for drainage and placement in well-aerated mist units with heating under the trays. It is essential that they are kept damp in the mist unit. Mimetes hirtus is not too difficult to root providing the correct methods are followed. Rooting may start after six weeks but can take up to three or four months.
In the event of callous formation but no roots, remove the cutting, damage the callous, and reapply rooting hormone. Place the cutting in a clean rooting medium and rooting should take place soon thereafter. Once the cuttings have rooted, they should be hardened off for three weeks, then planted into suitable containers.The planted cuttings should be kept wet at all times.
The planting medium should consist of sands with a high humic and low nutrient content. This can be attained by using black soil (when available) to which a small amount of peat (maximum 20%) can be added. Do not add compost to the soil. Add mulch on top of the planting soil in the container. Alternatively, a sandy fynbos mix can be created using acid river sand and composted pine bark or pine needles in equal parts.
Feed the plants every six weeks with ammonium sulphate and magnesium sulphate by dissolving three to four heaped teaspoons of each in 10 litres water and give each plant a cupful at a time. This will ensure a good balance of growth between roots and leaves. Water them regularly (at this stage they do not need their feet wet all the time but must not be allowed to dry out) and prune them after flowering; pruning will result in a fuller bush and hence more flowering shoots in the next season (Adriaan Hanekom and Anthony Hitchcock pers. comm.).
Pests:
Mimetes hirtus is very susceptible to the root rot fungus Phytophthora. In order to overcome this problem they should be planted in large pots in a sterilized planting medium. Water in the mornings as at this time the water applied is approximately the same temperature as the soil-avoid subjecting the plants to sudden changes in temperature as these may aid fungal growth. No other serious pests have been reported by Adriaan Hanekom, manager of the Caledon Fynbos Nursery.
Planting:
The plants may need toughening up prior to being planted out in a garden. Expose them to sunlight and fewer nutrients if necessary.
Anthony Hitchcock, Kirstenbosch Nursery Manager, recommends planting Mimetes hirtus along a shallow natural drainage line where extra runoff water accumulates. Provide protection from excessive heat by planting it together with plants that give a certain degree of cooling shade, for instance Chondropetalum tectorum, Elegia capensis, Erica perspicua, Osmitopsis asteriscoides and Psoralea aphylla. The soil should be mulched but not dug over, as this will disturb the roots.
Plants are usually available for sale at the Botanical Society's Annual Plant Fair at Kirstenbosch.
References
- Boucher, C. 1978. Cape Hangklip area II. The vegetation. Bothalia 12 :455-497
- Collins, B.G. 1982. Pollination of Mimetes hirtus (Proteaceae) by Cape Sugarbirds and Orange-Breasted Sunbirds. Journal of South African Botany 49 : 125-142.
- Eliovson, S. 1965. Proteas for pleasure: how to grow and identify them . Howard Timmins, Cape Town .
- Germishuizen,G. & Meyer, N.L. (eds). 2003. Plants of southern Africa : an annotated checklist. Strelitzia 14. National Botanical Institute, Pretoria .
- Goldblatt, P. & Manning, J. 2000. Cape plants. A conspectus of the Cape flora of South Africa . Strelitzia 9 . National Botanical Institute, Cape Town & Missouri Botanical Garden Press.
- Nichols, G. 2005. Growing rare plants . South African Botanical Diversity Network Report No. 36 : 51-53.
- Paterson-Jones, C. 2000. The protea family in southern Africa . Struik, Cape Town .
- Paterson-Jones, J.C. 1978. Mimetes. Veld & Flora 64 : 78-80.
- Rebelo, T. 1995. Sasol proteas: a field guide to the proteas of southern Africa . Fernwood Press, Vlaeberg, Cape Town .
- Rebelo, T. 2000. Field guide to the proteas of the Cape Peninsula . Protea Atlas Project, Cape Town .
- Rebelo et al. 2006. African Proteaceae Red Data List . South African National Biodiversity Institute, Cape Town . Unpublished material.
- Rourke, J.P. & Lincoln, T. 1982. Mimetes: an illustrated account of Mimetes Salisbury and Orothamnus Pappe, two notable Cape genera of the Proteaceae . Tiyan Publishers, Cape Town .
- Rourke, J.P. 1984. A revision of the genus Mimetes Salisb. (Proteaceae). Journal of South African Botany 50 : 171-236.
- Van der Zeyde, A. 1984. Sukses met Mimetes hirtus (L.) Salisb. ex Knight, op Bettysbaai. Veld & Flora 70 : 71.
- Vogts, M. 1958. Proteas: know them and grow them: on the cultivation of the South African Proteaceae . Afrikaanse Pers-Boekhandel, Johannesburg .
- Vogts, M. 1982. South Africa 's Proteaceae: know them and grow them . Struik, Cape Town .
Credits
Caitlin von Witt
Custodians of Rare and Endangered Wildflowers (CREW)
March 2006
Plant Attributes:
Plant Type: Shrub
SA Distribution: Western Cape
Soil type: Sandy, Loam
Flowering season: Spring, Winter
PH: Acid, Neutral
Flower colour: Red, White, Yellow, Orange
Aspect: Full Sun
Gardening skill: Challenging
Special Features:
Attracts birds
Good potplant
Wet sites
Horticultural zones
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