Tuesday, May 06, 2008

Adenandra obtusata Sond


Family: Rutaceae (Citrus family) Showy, white flowers that shimmer in the sun brighten up this evergreen shrub and attract insects, butterflies and bees to your garden. Belonging to the Rutaceae family (citrus family), Adenandra obtusata can be recognized by the scent it releases from oil glands when the leaves are touched or crushed. DescriptionAdenandra obtusata forms a robust, single stem upright shrub and grows to a height of 30-50cm. With its showy flowers and aromatic foliage it forms an ideal plant for your garden. The flowers buds are pink-red in colour and look like cherries on the bush. The reverse of the petals is flushed pink and the inside white, giving a very attractive effect. The flower has five petals marked with a purple throat. Flowers occur solitary or in clusters of up to 4 flowers at tips of branches and form glutinous (sticky) heads. They are subsessile (almost stalk less) or sessile (lacking a stalk). Peak flowering occurs from autumn to spring. Leaves are dull green, smooth on top with a clear whitish-green mid-vein below. Leaves are oval in shape, 5 x 3mm. Leaves are erect to spreading, oblong, overlapping (imbricate) with thickened margins rolled back and downwards (revolute). Look closely and you can spot a few glandular spots on the margin. Leaves closer to the tip of the branch are more crowded together. Young shoots develop at the tips of branches and these are ideal for cuttings. Fruit develop after flowering and are round capsules with 5-chambers bearing one shiny black seed per chamber. Seed heads become sticky. Seed are collected upon ripening when the seed capsule becomes harder and dark green in colour. DistributionAdenandra obtusata is endemic to Southern Overberg and grows naturally on rocky, coastal and inland slopes from Bredasdorp to Swellendam. It is found growing on coastal fynbos, flats and limestone hills at low attitudes and abundant on hard on exposed hills of hard limestone at Cape Agulhas. It only extends some 25 kms inland and is unlikely to be frost hardy, but the fact that it grows naturally in limestone locations suggests that it might be easier to cultivate in the garden than species from nutrient poor, acid sandstone. Derivation of name and horticultural aspectsThe genus name of Adenandra derived from the Greek meaning aden, a gland; ander, a man. The specific name means "blunted" and may refer to the leaves. EcologyThis plant is pollinated by insects. It is not clear what role the oil glands play. Uses and cultural aspectsAdenandra obtusata is best used as garden plant and flowering stems can be used in floral bouquets or in a mix bunch of flowers displayed in a vase. Growing Adenandra obtusata Adenandra obtusata is best planted as a filler plant between taller shrubs and a herbaceous border. Allow enough space to ensure growth and to prevent being squashed by faster growing plants. It requires a sunny spot, well-prepared soil, enriched with compost and a well-balanced fertiliser. Buchus naturally occurs in a mixed fynbos and ideally should be used in this way in a garden. Plant buchus with companion plants such as Restios, Pelargoniums, Helichrysum and smaller buchu species e.g. Acmadenia heterophylla, Agathosma ciliaris, Agathosma ovata “Kluitjieskraal”, Agathosma glabrata and Agathosma lanceolata. It can be used as a border plant, planted in masses, filler plant and as a good pot plant. Planting buchus into your garden is best done after the first good winter rains have started (May to August). Buchus respond to fairly dense plantings, which helps to retain soil moisture. An annual mulching of well-rotted compost is advised to reduce weeds and keeps the soil temperature low. Buchus can be grown from seed or cuttings. Fresh buchu seed is sown in autumn. The seed are sown into a tray containing a well-drained medium of equal portions of sand, loam and compost. Use some of the medium to cover the seed and water. Place in a covered area with good light and air circulation. Keep medium damp. Germination occurs in 1 to 2 months.
Young seedlings are pricked out into 0,5 l bags when 4 true leaves have developed, using a fynbos medium. Pinch out the growing tips of the seedlings to encourage bushy growth. Flowers are produced after two years. Cuttings have the advantage of producing a larger flowering plant quicker than seedlings. Tip cuttings, 50-70 mm, are taken from the current year's growth. Prepare cuttings by making a clean cut below the node and remove the third of the foliage. Dip the base of the cutting in a rooting hormone such as Seradix 2. Firmly place the cuttings in a medium of 50% bark and 50 % polystyrene. Ideally these cuttings should now be placed in an well-aerated propagation unit with a bottom heat of 24-degree Celsius. Rooting occur in 9 to 11 weeks. Carefully pot the rooted cuttings using a well-drained humus riched fynbos-potting medium (2 parts leafmould, 1 part coarse sand). Plants will be ready for planting in 7 to 8 months. Feed regularly with a well-balanced nutrient. Yellow leaves can be treated with an application of iron chelate. The genus Adenandra displays large showy flowers but is less scented than the other genera. There are 18 species found in this genus and endemic to the South-Western part of the Cape Province . Other interesting species Adenandra gummifera forms an upright single stemmed shrub and grows to a height of 0,4m to 1m. Bears white flowers with a pink reverse at the tips of branches. It is endemic to Bredasdorp and occurs on steep, sandstone slopes of Potberg. It grows in the same area as A.obtusata, but is found in the acid, sandstone locations whereas the latter prefers the limestone localities. Author; Norma Jodamus Kirstenbosch NBG

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