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HBrooks780/sandbox
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Genus: Senecio
Species:
S. glastifolius
Binomial name
Senecio glastifolius
L.f. (1782)
Synonyms[1]
  • Jacobaea glastifolia Schrank (1822)
  • Senecio serratulifolius Weinm. (1828)

Senecio glastifolius is a species of flowering plant in the aster family known by the common names woad-leaved ragwort,[2] holly-leaved senecio, and pink ragwort. A tall perennial herb, it is endemic to the Cape Provinces of South Africa, and it is cultivated as an ornamental plant for its colorful flowers. It has been known to escape cultivation and become naturalized in areas of appropriate climate; it can be found growing wild in parts of New Zealand and Australia.[3][4]

It favours a Mediterranean climate, often coastal, typically colonizing disturbed soil. It is an annual herb producing a single, erect, branching stem which grows to a height 1 to 1.5 metres tall, and 50 cm wide, with the main stem growing to be up to 8cm thick at the base, before branching off into smaller, thinner branches that are widely spread[5]. The serrated leaves are often more coarsely toothed near the leaf base, and feel prickly. The inflorescence bears flower heads lined with black-tipped bracts. They contain a yellowish disc at the centre, with mauve petals. Senecio glastifolius is sometimes confused with Senecio elegans, (which also grows by the coast), but the leaves of the two species are different.

Species Description

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As part of the Asteraceae family, S. glastifolius has prominent radiate capitula flowers, meaning the flowers have ray petals that are arranged around the yellow disk center. The flowers on S. glastifolius plants range from purple to white in colour and there are multiple of these flowers coming off one branch[6].

The leaves of a S. glastifolius plant are light green and oval with serrated edges. The leaves range from 3-15 cm long, with larger leaves at the base of the plant, getting smaller further up the main stem of the plant[5]. Leaves on S. glastifolius are amplexicaule, meaning the base of the leaf is clasping and wrapping around the stem[7].

Senecio glastifolius has small, rounded fruit which do not release seeds, 2.5 mm long, called cypselae which are a defining feature present in all species that are a part of the Asteraceae family[8]. S. glastifolius also has pappi which are 7.9 mm long attached like a ring around the top of brown seeds that are 2 mm long[5]. Pappi are small tufts of hair with the key role to assist in wind dispersal of seeds[9].

 
Senecio glastifolius plant in full flower

Geographic Distribution and Habitat

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Natural Global Range

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The native range of S. glastifolius is quite small, in the Cape region in the west of South Africa[10]. Senecio glastifolius has now spread throughout the United Kingdom, Australia, New Zealand and the region Maderia in Portugal[10]. Senecio glastifolius has spread across the globe now and is classified as an invasive species in all countries[10].  

New Zealand Range

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Since entering New Zealand, S. glastifolius has spread throughout both the North and South islands, along both the east and west coasts, as well as more inland, which is different from its usual habitat in South Africa[10]. Senecio glastifolius was first recorded in Gisborne in 1963, and then in multiple locations surrounding Wellington in the same year[10]. By the late 1960s, Senecio glastifolius spread quite far in the Wellington region, and the upper South Island[10]. 1972 was the first recording of S. glastifolius being present in the Hawkes Bay area, in Havelock North[10]. In 1975, it was declared to be a ‘local weed in waste areas’ in Palmerston North[10]. Senecio glastifolius has also been recorded on multiple islands that are at least 2.5 km from mainland, such as Matiu/Somes Island and Mana Island, near Wellington[10]. In the 1990s Senecio glastifolius spread to Whanganui, which is significant in the spread of S. glastifolius, as it then quickly spread down the coast towards Wellington[10]. 1992, it was officially recorded to be present in Hamilton, which was the furthest north and inland so far in New Zealand, however, there is a recording of it being present uploaded on iNaturlist Southwest on Mt Karioi near Raglan in January in 2023 by elcumming[11]. Senecio glastifolius has been recorded on iNaturlist 845 times in New Zealand alone with majority of these observations are recorded in the lower North Island[12]. The first time it was recorded in New Zealand was in 2006 by jon_sullivan at Island Bay, South of Wellington, and the most recent recording of S. glastifolius in New Zealand on iNaturlist was only May 7, 2024, by arnim at Foxton Beach[13][14]. Senecio glastifolius is now primarily spread throughout the lower North Island, but is also recorded in the South Island, with Dunedin being the farthest South, recorded on iNaturlist in October 2017 by johnsteel, and Hamilton the most northern known sites of S. glastifolius[15][10].  

Habitat Preferences

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In South Africia, S. glastifolius is only found at high altitude, up to 1,100 meters, in mountain ranges that are located close to the coast, no more than 50 km inland[5]. Growing at high altitudes means S. glastifolius is highly resistant to wind and prefers colder winter climates and year-round rainfall[5]. It is found in various habitats, including rocky mountainsides, along the banks of streams, marshy swamp areas, and can grow in recently planted plantations and pastoral areas, making it a problem for the South African agricultural sector[5]. Throughout Australia, Maderia and locations in the United Kingdom, S. glastifolius has only been found near the coast, unlike in New Zealand. Senecio glastifolius grows in vastly different habitats within New Zealand and is proving to be concerning as to how it is fast it is evolving to be able to habitat a broader range of habitats[5]. Senecio glastifolius is growing more inland in New Zealand, and closer to sea level instead of at altitude, as observed in South Africa[5]. In New Zealand, S. glastifolius is also growing in areas where there is less rainfall annually, between 800 to 1 600 mm, where it is also warmer, 10–15 °C[5].

Life Cycle/Phenology

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Senecio glastifolius tends to flower during spring months, September - November in New Zealand[16]. The small seeds in S. glastifolius are about 2 mm long and are produced from late summer into early autumn[16]. The main form of seed distribution is via wind dispersal, due to how small and therefore light they are[10]. During this wind dispersal, the pappus remains attached to the seeds[10]. Although germination of seeds that have spread via seed distribution is the main form of reproduction for S. glastifolius, the species can also reproduce through fallen branches forming roots and growing. Soil contaminated with S. glastifolius seeds that has been transported and moved to new locations is also thought to be a key factor in the spread of S. glastifolius throughout mainland New Zealand[10].

In the native range of S. glastifolius in South Africa in 1998 La Cock et al. (1999) found that maximum germination of S. glastifolius occurred when the temperature averaged above 25°C. This germination occurred in February, and then seedlings appeared in July/August, during a warm and wet winter climate[5].  Senecio glastifolius seeds appear to have some persistence in soil seed banks, but not for an exceptionally extended period time[17].

Diet, Prey and Predators

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Diet and Foraging

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Seedlings of S. glastifolius tend to sprout and grow in groups/clusters in bare ground where grass growth is suppressed, usually in openings of canopies or on the margin of bushes[5]. Seeds also sprout following fires and then substantial rain. The S. glastifolius seeds can grow in poor soil which has little-to-no nutrients, however, have only some tolerance to soils that have high levels of moisture, and do not grow at all in areas that are permanently saturated[17]. Senecio glastifolius mainly grows in soils with large soil particles, such as scree, river gravel, sand, yellow-brown earths and on rocky banks[17].

Predators, Parasites and Diseases

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The leaves of S. glastifolius are eaten by the larvae of the magpie moth, and the diurnal moth feeds on the flowers of S. glastifolius[5]. Senecio glastifolius appears to be edible and possibly enjoyable for sheep to feed on[5].  

Although there is minimal study done into the S. glastifolius species, it is expected that S. glastifolius is a toxic and potentially harmful plant, as is the majority of the Senecio genus, and so not many species feed on the plant[18]. Poisoning from the Senecio genus can come from contamination of medicine, honey containing pollen from Senecio flowers and water, and will affect the liver and abdominal fluid, which can lead to death in serious cases[18].  

Other Information

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The name Senecio is from Latin origin meaning ‘old man’, which is suspected to refer to the bearded and hairy appearance of the seeds of S. glastifolius[16].

Senecio glastifolius is a vascular plant, meaning that there is a system of “tube-like veins” running all throughout the plant that have the role of transporting nutrients and water to and from various parts of the plant, such as roots, stems and leaves[19]. A vascular system is common within large plants, such as S. glastifolius, and has two main sub-systems: xylem and phloem[19]. The xylem system is responsible for transporting water and minerals that enter the plant via the roots from the soil, and so have quite thick cell walls. The phloem system is mainly responsible for transporting food nutrients and other substances like growth regulators[19]. The vascular systems can clearly be seen in the leaves of S. glastifolius, and look like veins running from the center stem out to the edges, more evident on the underside of the leaf[19].

Once S. glastifolius has flowered two or three times, the plant becomes very top-heavy, and eventually falls over, usually breaking just above ground level, where the main stem and roots meet[5]. Sometimes this fallen section of the plant remains attached to the roots and continues to grow. The roots also regrow a new main stem and bush, resulting in the plant appearing to have multiple ‘layers’[5]. Senecio glastifolius can do this two or three times before the whole plant eventually dies, resulting in S. glastifolius having a relatively short lifetime[5]. Currently there is no evidence found of S. glastifolius plants being older than 4 years. The fallen section of the S. glastifolius may occasionally form its own new root system into the ground where it has fallen horizontally and continue to grow through its own root system[5].  

 
Leaves of Senecio glastifolius, showing the distinctively serrated margins
 
Botanical illustration of Senecio glastifolius

References

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  1. ^ Senecio glastifolius L.f. Plants of the World Online. Retrieved 9 October 2023.
  2. ^ BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
  3. ^ P.A. Williams (1999). "Biology and ecology of Senecio glastifolius and its spread and impacts in New Zealand" (PDF). Science for conservation 112. Department of Conservation. Retrieved 24 Jul 2013.
  4. ^ "Weed management guide - Holly leaved senecio (Senecio glastifolius)" (PDF). Department of the Environment and Heritage. Retrieved 24 Jul 2013.
  5. ^ a b c d e f g h i j k l m n o p q La Cock, G; Ogle, C.C; Reid, T; Timmins, S.M; Williams, P.A (1999). Biology and ecology of Senecio glastifolius and its spread and impacts in New Zealand. Department of Conservation.
  6. ^ Zhang, Teng; Elomaa, Paula (February 2021). "Don't be fooled: false flowers in Asteraceae". Current Opinion in Plant Biology. 59: 101972. doi:10.1016/j.pbi.2020.09.006.
  7. ^ HarperCollins Publishers (May 2024). "Definition of 'amplexicaul'". Collins English Dictionary.
  8. ^ Marzinek, Juliana; De-Paula, Orlando Cavalari; Oliveira, Denise Maria Trombert (September 2008). "Cypsela or achene? Refining terminology by considering anatomical and historical factors". Revista Brasileira de Botânica. 31 (3): 549–553. doi:10.1590/S0100-84042008000300018. ISSN 0100-8404.
  9. ^ Merriam-Webster (May 2024). "Pappus". Merriam-Webster.com Dictionary.
  10. ^ a b c d e f g h i j k l m n Beautrais, Josef Rehua (2013-01-01). The geographic distribution of Senecio glastifolius in New Zealand: past, current and climatic potential (Thesis). Open Access Te Herenga Waka-Victoria University of Wellington. doi:10.26686/wgtn.17005594.v1.
  11. ^ elcumming (15 January 2023). "Woad-leaved Ragwort (Senecio glastifolius)". iNaturlist.
  12. ^ "Observations". iNaturlist. May 2024.
  13. ^ jon_sullivan (1 June 2006). "Woad-leaved Ragwort (Senecio glastifolius)". iNaturlist.
  14. ^ arnim (7 May 2024). "Woad-leaved Ragwort (Senecio glastifolius)". iNaturlist.
  15. ^ johnsteel (26 October 2017). "Woad-leaved Ragwort (Senecio glastifolius)". iNaturlist.
  16. ^ a b c "Senecio glastifolius". New Zealand Plant Conservation Network. May 2024.
  17. ^ a b c Brooks, K; Brown, K (September 2002). Weeds Book-2. Environmental Weed Actions Network.{{cite book}}: CS1 maint: year (link)
  18. ^ a b Sadgrove, Nicholas John (2022-12-13). "Comment on Pyrrolizidine Alkaloids and Terpenes from Senecio (Asteraceae): Chemistry and Research Gaps in Africa". Molecules. 27 (24): 8868. doi:10.3390/molecules27248868. ISSN 1420-3049. PMC 9781224. PMID 36558004.{{cite journal}}: CS1 maint: PMC format (link) CS1 maint: unflagged free DOI (link)
  19. ^ a b c d "What's a vascular plant?". New Zealand Plant Conservation Network. May 2024.
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Wikimedia Commons has media related to Senecio glastifolius.

Senecio glastifolius description from New Zealand Plant Conservation Network

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