Its form is a dense tangled shrub 2 metres (6.6 ft) tall[19] or a climber that can reach 6 metres (20 ft) high, if suitable support is available.
The alternate leaves are rhombic to ovate (diamond-shaped or egg-shaped),[20] 3 to 5 centimetres (1.2 to 2.0 in) long and 1 to 5 centimetres (0.39 to 1.97 in) wide and occur in 1-4 pairs. They are thick, glossy, fleshy and coarsely toothed, with one to three teeth each side[3] and bluntly lobed,[19] with upper leaves becoming smaller with fewer teeth or none at all.[3] They have a frosted look from a powdery coating on the lower side.
Leaf stalks are 1 to 4 centimetres (0.39 to 1.57 in) long.[8]
The stems are succulent, and are often variegated with pale yellow green and purple, which become woody as they age.[21] They are slightly angular (not upright) and usually sparingly branched.[3] Neither stems nor leaves are hairy.[3][8]
Inflorescence
Inflorescence
Senecio angulatus produces numerous flowers in open clusters at the end of its branches or stems.[3] The honey-scented flowers are on an elongated stem and open in succession from the base up as the stem continues to grow. The flower clusters are more flat at the top than pyramid-like, and are 4 to 8 centimetres (1.6 to 3.1 in) in diameter.[8] Often the cluster droops with the flower heads at the end of the cluster turning upwards.
Flower stalks are mostly hairless or with some short hairs, 6.5 to 10.5 millimetres (0.26 to 0.41 in) long. Attached to flower stalks are 8-11 fine pointed bracts 5 to 6 millimetres (0.20 to 0.24 in)[3] which are surrounded by 4-7 pale green and sometimes purple tinged supplementary bracts at the base, 1.5 to 2.5 millimetres (0.059 to 0.098 in) which make a cup shape around the base of the involucre.
Individual flower-heads are radiate and urn-shaped.[8] The corolla has a disc[3] comprising 10-15 dull golden yellow disc florets.[8] Each disc floret is a hairless tube with a slight expansion below the middle and lobes 1.3 to 2 millimetres (0.051 to 0.079 in) wide. 4-6 ray florets surround the disc florets and have yellow[3]ligules
(that look like petals) 5.5 to 9.5 millimetres (0.22 to 0.37 in) long that make the flowers look daisy-like.[19]
An autumn-winter bloomer, the plant flowers from April to May in Southern Africa and May to July in Australia.[8] In New Zealand, it blooms from March to August.[22] In the northern hemisphere, particularly in Italy and Spain, it flowers from November to the end of January.[23][24] In very sunny spots, it can have sporadic blooms in late spring.[25]
Fruits and reproduction
Cape ivy is easily dispersed by wind-blown seed, stem fragments, dumped garden waste and by the expansion of the plant through runners.[19]Achenes are 3 to 4 millimetres (0.12 to 0.16 in) long,[3] ribbed or grooved with short hairs in the grooves[3] and a tapering cylindrical shape.[3][8] The parachute-like hairs, the pappus, are 5 to 7 millimetres (0.20 to 0.28 in) long.[3][8]
Cape ivy was introduced in Malta in the 15th century as an ornamental plant.[30] In Queensland, the plant may have increased in popularity following the Boer War, as there were anecdotal accounts that it was introduced from South Africa by the soldiers who returned to Australia after 1902. Moreover, it was displayed in garden pillars in Brisbane newspapers between 1906 and 1910, praising the plant for the beauty of both its foliage and its yellow clusters of blooms. Though these reports may have falsely applied the S. angulatus name to Senecio mikanoides, which was a weed at that time on the east coast.[31]
It was most likely introduced to the United States after 1930, as it is not listed in the first edition of Hortus, although it is rarely cultivated in that country.[32] The plant was collected as a weed in Melbourne's southern suburb of Mornington in 1936, and was displayed in newspaper column submissions in areas between Bendigo and Swan Hill in the 1940s and 1950s. In Melbourne metropolitan area, it became prevalent on coastal banks and on decomposed rock gullies of suburban creeks.[31] It was introduced in New Zealand in 1940 as an ornamental.[9]
Propagation
Cape ivy grows in USDA hardiness zones 9a through 11b, tolerating temperatures between 10 °C (50 °F) and 38 °C (100 °F),[22] and is medium to fast-growing. Drought and heat tolerant, it would flourish better with some water in the summer and would bloom more often in full sun. It can grow indoors as a houseplant, provided it gets some sunlight. Pruning is necessary as the plant can become limp when it gets taller.[33]Propagation can be done by cuttings (as the plant easily roots from the branch tips), and this is to be conducted between spring and fall. Seeds prefer consistent moisture and warm temperatures to germinate. Annual fertilisation is necessary, though not mandatory. Pests include aphids.[34][35]
Chemistry
Seeds are reported to be unviable and that the predominate mode of dispersal is vegetative reproduction – In a 2001 Wellington study, artificially pollinated stigmata varnished with aniline blue under a UV microscope displayed that a low number of pollen grains corresponded to the stigmatic surface.[22]Callose occurred in the few pollen tubes that did adhere to the surface, hinting the presence of a sporophyticself-incompatibility mechanism, which aids the theory that S. angulatus and Delairea odorata consist of a single genotype (or are set for a single S allele), thus seed is incapable of being produced.[22][36]
Naturalisation at a scrubland in JordanCultivated at an apartment complex in Jerusalem
Cape ivy is native to the Cape Province in South Africa, hence its name, and it has been naturalized in parts of South Italy, France, Spain, Croatia, Portugal[13][32] and some coastal areas in southeastern Australia (particularly the Mornington Peninsula),[37] where it is spreading.[8] It is reported to be invasive in New Zealand.[9] In Australia, it is a significant environmental weed in the state of Victoria, and an emerging weed in South Australia, Tasmania, New South Wales and Western Australia (where it is declared an alien species).[38][39] In California, Albania and Chile, it is reported to be escaping.[32]
It can become aggressive when it is established, where it may smother the existing native vegetation both in the ground layer and canopy, thus altering the light climate in the invaded community and sometimes suppress the regeneration of native plants.[19] As such, the plant is targeted by the Oregon Department of Agriculture for early detection and fast response if it were to escape from cultivation.[32]
On the Costa Brava in Spain, it was one of the five most recorded species, where it was found in large assemblage, usually close to human residence, invading and colonizing the clifftops, roadsides and the proximate scrubland, including the undergrowth, replacing native flora species such as Pistacia lentiscus. It was introduced to Catalonia in the 1970s as a groundcover plant in home gardens, before escaping. Although it is not recorded as an invasive species in the Spanish Catalogue of Invasive Species, it is one of the most common alien species present on the Catalan coast as it clearly possesses invasive behaviour.[40]
^"Cape ivy (Senecio angulatus)". Controlling problem weeds in riparian zones. Greater Wellington Regional Council. 2004. Archived from the original on October 15, 2008. Retrieved 2008-03-31.
^Senecio angulatus L.f. Western Australian Herbarium (1998–). Florabase—the Western Australian Flora. Department of Biodiversity, Conservation and Attractions. Retrieved 12 December 2023.
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