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Home , Amellus, Ampelaster, Asteraceae, Astereae, Aster (genus), Aster amellus

nomenclature

The splitting of

The increasingly widespread acceptance Tim Sandall / RHS of classification changes in Aster will result in new names for Michaelmas daisies and their relatives

In 2015 the RHS had all been regarded as part of the genera and 25,000 . By the large Aster, which at one time second edition in 2007 the number will adopt the new contained about 500 species. of genera had increased by about scientific name for 500 to 1,600 while the number of Shrinking genera species remained about the same. Michaelmas daisies, In recent , taxonomists have What has been the impact of this as well as other removed clusters of species from trend on the names we use in the large genera in the to form garden? Many of us can remember changes in Aster. smaller, more easily comprehensible when what we now know as Julian Shaw units. The table below shows the ‘Sunshine’ was general shrinkage of several large ‘Sunshine’. We have also come to explains why Asteraceae genera as more numerous, accept rather than smaller genera have been established Senecio for a genus of bedding , ichaelmas daisies are or expanded. The figures given in the instead of Aster for those blue perhaps the most familiar two editions of Heywood (1978, South African daisies, and Argyranth­ M plants currently grown 2007) summarize the situation. In emum rather than for under the Aster label. Mainly 1978 the first edition recorded 1,100 bedding marguerites. of A. novae-angliae and A. novi-belgii, they are a key element in gardens, Changes in number of species in large asteraceae genera giving colour to bright autumn days 1973 1994 2008 2011 in the northern hemisphere. There Aster 500 250 180 152 are many cultivars available, in a wide 1,200 48 41 45 Senecio 2,000–3,000 1,250 1,000 1,200 range of shades including white, 1,000 500 750 17 blue, purple, pink and shades of red. Sources: Willis (1973), Bremer (1994), Mabberley (2008), Shiet al. (2011). Until recently, Michaelmas daisies

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Why the changes? will be given in the book, and it is Many of the large genera traditionally hoped that the horticultural industry accepted in flowering plants are and gardeners will become familiar assemblages of species left over after with and use the new names. more distinctive clusters of species have been removed. This includes Aster reshapes the horticulturally important Aster The species of the genus Aster and Senecio. Rather than consisting is Aster , a south European of homogenous units linked by species sometimes known as Italian characters held in common, these aster. This is the species to which genera tend to be artificial groupings the name of the genus is permanently holding the less distinctive remnants Sleigh / RHS Mike linked. This means that if the genus of a tribe. In effect, these large genera is the type species of the genus, so is split up then A. amellus (and its of remnants represent unfinished will retain its name, along with its close relatives closest relatives) is the species that taxonomic business. This is not the opposed to superficially similar, are keeps the Aster name. Other garden best way to construct a useful grouped together. Hence the plants that keep the Aster name . While there have been classification is more useful, include European species such as several attempts to propose division particularly in areas that rely on the A. thomsonii and its hybrid with of these large genera into smaller predictive nature of taxonomy, such A. amellus, A. x frikartii. Aster pyrenaeus units, they have not been upheld by as conservation, breeding and also keeps its name. Incidentally, the more recent molecular data. the search for natural products. In ‘Lutetia’ which is often listed Although a certain amount of reality, the problem lies not with the under A. pyrenaeus, appears to progress in understanding new classification and new names, represent a selection of A. amellus relationships between species in but in the limited knowledge and (Picton 2004). Aster was made using morphology mistaken ideas of the past that can Aster , sea aster, a UK and chromosome morphology (Jones tenaciously hold us in their grip. native, becomes Tripolium 1980, 1983; Semple & Brouilllet pannonicum, the only species in its 1980), it was only after studies Coming soon genus. Aster sedifolius has become analyzing variation in chloroplast The new classification of Aster has part of the Eurasian genus , and nuclear DNA that real progress been used in the recent Flora of consisting of 40–50 species. began (Xiang & Semple 1996). More (Barkley et al. 2006) Some Asiatic species, including recent work has focused on nuclear and Flora of (Shi et al. 2011), A. glehnii and A. dimorphophyllus ribosomal DNA internal transcribed and is appearing in new regional from Japan, and A. taiwanensis from spacer (ITS) sequences, such as a floras in America such as the Flora of Taiwan, are likely to form new genera. study by Brouillet et al. (2001) that (Yatskievych 2005), and A recent study by Li et al. (2012) has employed data from 326 accessions. also in the influential Euro+Med demonstrated that many well known These studies indicate that Aster PlantBase database (Greuter 2003). Chinese species currently in Aster in the old sense was a mixture of Mindful of the impact that the actually represent three new species from all over the world that proposed name changes would have unnamed genera that are closely were not particularly closely related, on a popular group of plants, the related to Australasian species. and really belonged in other smaller RHS Nomenclature and Taxonomy African asters also comprise genera. Reflecting these results in Advisory Group (NATAG) has been several genera. The Madagascan the names of the plants has resulted monitoring the adoption of the new species are referred to Madagaster, in describing new genera, resurrect­ classification by the international Aster comptonii to Afroaster, and ing old genera, and raising infragen­ botanical community over the past Aster capensis and Aster harveyanus eric taxa to generic rank, all of which 10 years. After considering the still await placement. creates unfamiliar new names. evidence and noting the widespread The North American species While this might initially give rise acceptance of the new taxonomy, form a single large grouping that to some inconvenience, it does NATAG has recommended its splits in to many genera, including reflect a more realistic classification. adoption for the 2015 edition of the the horticulturally important Plants that are genuinely similar, as RHS Plant Finder. Cross references , and ➤

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Symphyotrichum, the last containing There are several more genera to be (1964), Cullen et al. (2000), Picton the majority of Michaelmas daisies. separated out of it, even in . (2004) and Shi et al. (2011). South American asters have also The only certainty is that A. amellus been divided up, with several species and its close relatives remain Doellingeria now in , and others in permanently in Aster. Helpful This genus of three species from genera such as , accounts of the cultivated and wild eastern North America consists of and . species can be found in Grierson hardy, herbaceous perennials. The

Genera in cultivation key to replacement aster genera in cultivation The new and unfamiliar genera that 1a Plant sprawling or -like, shrubby habit carolinianus are most widespread in 1b Plant herbaceous, annual or perennial, or alpine sub-shrub 2 are discussed below, and their 2a Dwarf alpine herb with fleshy tap root alpigenum distinguishing features are 2b Taller herbaceous plants or alpine subshrubs 3 highlighted. The descriptions are 3a Ray florets absent 4 quite technical as the genera tend to 3b Ray florets present 5 be separated on characters 4a pubescent, glandular Galatella (Linoseris) associated with the involucral , 4b Leaves hairless, without glands or . The table on p123 shows the new generic placement of 5a Ray florets sterile without styles Galatella 5b Ray florets fertile, 2 styles present 6 currently cultivated asters, along with a reference to a convenient flora 6a Involucral bracts in 2 indistinct rows, all nearly equal Aster where a description can be found. 6b Involucral bracts in 3–5 rows, often very unequal 7 7a Basal and some cauline leaves petiolate, lamina base cordate to subcordate Ampelaster Eurybia This is a genus of a single species, 7b Basal and lower cauline leaves petiolate, lamina base not cordate or A. carolinianus (syn. Aster carolinianus) sometimes sessile 8 from the region forming a 8a Stem with usually 10 or less capitula (flowerheads) 9 large sprawling or vining shrub with 8b Stem with more than 10 capitula (flowerheads) 11 weak stems to 4m long. It is usually 9a Capitula solitary, alpine to 15cm, dimorphic coloradoense evergreen, but deciduous in cooler 9b Capitula several, herbaceous perennial to 70cm or more, achenes uniform 10 areas. The leaves, 3-7 x 1-2cm, are 10a Outer involucral bracts obtuse to rounded; mid to upper stem leaves alternate, thin-textured, with bases narrowed at base Aster amellus and relatives clasping the stem. Around 1–15 10b All involucral bracts acute; stem leaves more or less auriculate, flowerheads with pale rose-purple semi-amplexicaule ray florets, 1–2cm long, are held in 11a Annual or biennial; ray florets about equal length to pappus panicles. The involucral bracts, Symphyotrichum squamosum 30–50 in 5–6 series, are 1-nerved, the 11b Perennials; ray florets much longer than pappus 12 outer ones being linear-lanceolate to 12a Involucral bracts obtuse to rounded 13 spathulate, and the inner ones being 12b Involucral bracts acute or mucronate 14 linear-attenuate and unequal in size, green only near the apex, with 13a Leaves succulent, hairless Tripolium pannonicum 13b Leaves not succulent, hairy Aster amellus and relatives margins hyaline towards apex. In the wild it grows in wet areas 14a Involucral bracts 1-nerved, with orange resinous mid-vein; pappus of with a peak flowering in winter. It is 4 whorls*, the outermost very much shorter not hardy and makes an unusual 14b Involucral bracts 1–3-nerved; pappus of 1(–3) whorls of 20–50 subequal, barbellate bristles Symphyotrichum conservatory plant with winter interest in frost-prone climates * Sometimes described as a ‘double pappus, inner row of scabrid bristles, outer row of much shorter bristles’ (Bremer 1994), or ‘multiseriate, outer series of short Aster setae, 2 inner series of long barbellate bristles’ (Semple et al. 2002), but Barkley et al. (2006) note ‘4 series, whitish, outer very short scales, inner 3 of 60–90 white to The species in this reduced genus are tan barbellate bristles’. best regarded as work in progress.

122 June 2014 PlantsmanThe single cultivated species, D. umbellata 5–9mm long. The involucral bracts, Eurybia are rhizomatous, hardy, (syn. Aster umbellatus) can reach 2m 16–40 in 3–5 series, are 1-nerved, herbaceous perennials to 1.2m tall. tall and is distinguished by its flat- lanceolate to deltoid, unequal in The leaves are either heart-shaped topped corymb of many, small, length, with narrowly scarious to triangular with cordate bases white-rayed flowerheads and elliptic margins and rounded apices. The (E. divaricata, E. x herveyi, E. macro­ leaves that are scabrid above. The achenes are compressed, obconic, phylla and E. schreberi) or spathulate 4–15 ray florets are white and with 3–5 ribs and sparse, long hairs. to ovate with tapering bases The pappus has two types of bristle; (E. siberica, E. spectabilis), and have Aster schreberi now belongs to a smaller few in the outer ring about 0.5mm narrow petioles. The flowerheads genus and becomes long, and three inner rings of many are usually borne in corymbs. The bristles, 3–4mm long (see also the involucral bracts, 20–140 in 3–7 rows, note at end of key on p122). are 1-nerved, broadly ovate to oblong or oblanceolate, lanceolate or linear, Eurybia are unequal in length with their This is a genus of 23 species from apices obtuse to acute. The ­ North America and north Eurasia. heads with 5–60, white to purple, ray It excludes a group of four species florets have a disk that matures from the Rocky Mountains recently to purple. The achenes are obconic

Tim Sandall / RHS Sandall Tim placed in their own genus, . to fusiform, compressed, with ➤

Name changes for Aster species listed in RHS Plant finder 2013 Name in Aster Generic placement or new name References Name in Aster Generic placement or new name References acris Galatella sedifolia subsp. sedifolia FE novi-belgi Symphyotrichum novi-belgi FE, FNA ageratoides Aster trifoliatus subsp. ageratoides FE oblongifolius Symphyotrichum oblongifolium FNA alpigenus FNA oolentangiensis Symphyotrichum oolentangiense FNA alpinus Aster FE peduncularis Aster G64 amellus Aster (type of genus) FE pilosus x amethystinus Symphyotrichum x amethestinum FNA – var. demotus – var. pringlei FE, FNA carolinianus Ampelaster carolinianus FNA puniceus FE, FNA ciliolatus Symphyotrichum ciliolatum FNA pyrenaeus Aster FE coloradoensis Xanthisma coloradoense FNA radula FNA cordifolius Symphyotrichum cordifolium FNA sagittifolius Symphyotrichum cordifolium FNA corymbosus FNA x salignus Symphyotrichum x salignum FE diffusus Symphyotrichum lateriflorum FNA scaber Aster FJ diplostephioides Aster FC, G64 scandens Ampelaster carolinianus FNA divaricatus Eurybia divaricata FE, FNA schreberi Eurybia schreberi FE, FNA dumosus FE, FNA sedifolius Galatella sedifolia FE, S02 ericoides FNA, FE sibiricus Eurybia sibirica FE, FNA falcatus FNA soulieri Aster G64 foliaceus Symphyotrichum foliaceum FNA spathulifolius Aster FJ – var. parryi – var. parryi FNA spectabilis FNA x frikartii Aster squamatus Symphyotrichum squamatum FE furcatus FNA stracheyi Aster FC, G64 glehnii Aster FJ subcaeruleus FC greatae FNA tartaricus Aster FNA, FJ x herveyi Eurybia x herveyi FNA thomsonii Aster G64 himalaicus Aster FC, G64 tongolensis Aster FC kotarimus name not traced tradescantii Symphyotrichum tradescantii FNA laevis Symphyotrichum leave FE, FNA trinervis Aster FNA, G64 lanceolatus Symphyotrichum lanceolatum FE, FNA – var. harae Aster FJ lateriflorus Symphyotrichum lateriflorum FE, FNA tripolium Tripolium pannonicum FE linosyris FE turbinellus Symphyotrichum turbinellum FNA maackii Aster FC, FJ umbellatus Doellingeria umbellata FNA macrophyllus FE, FNA vimineus Symphyotrichum lateriflorum mongolicus Aster FC var. lateriflorum FNA novae-angliae Symphyotrichum novae-angliae FE, FNA x versicolor Symphyotrichum x versicolor FE Key to references FC = (Shi et al. 2011) FJ = Flora of Japan (Iwatsuki et al. FNA = Flora of North America G64 = Grierson (1964) FE = Flora Europaea (Grierson 1975) 1995) (Barkley et al. 2006) S02 = Semple et al. (2002)

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7–12 nerves, and strigillose. The pappus is reddish, tawny-pink, consisting of unequal length bristles that are often club-shaped, in 2–4 series.

Galatella This is a genus of herbaceous perennials from Europe and Asia with 40–50 species. Growing to a height of 0.5–1m and with densely leafy stems, they have finely pubesc­ Carol Sheppard / RHS ent stems and leaves. The leaves are Simon Garbutt / RHS 1.5–6 x 1–6mm, with glandular dots and prominently 1-nerved (although lower leaves sometimes 3-nerved). The flowerheads are held in corymb­ iform arrays with 1–4 per short relatives in Linoseris (syn. Crinitaria), to linear in the inner series, unequal branch, each with 3–10, lavender to along with Tripolium, are more to almost equal in length, usually violet ray florets that are 10x 1mm closely related to than they are 1-nerved (rarely 3-nerved), not keeled, and sterile with aborted or absent to the rest of the tribe (Fiz with the green zone on the back styles. The involucral bracts are in et al. 2002, Li et al. 2012). usually diamond-shaped and often 3–4 imbricated series; the outer, elongated towards the base. The ovate-lanceolate ones being one- Oreostemma achenes are obovoid or obconic, third as long as the inner, linear- This is a genus of three species of somewhat compressed, with 3–5 lanceolate ones, and all are 3-nerved, alpine herbs from northwest North nerves. The pappus consists of acute, ciliate towards apex and with America, and O. alpigenum is some­ 20–50, white to brown, equal membranous margns. The achenes times cultivated. It is distinguished bristles in usually one series. are cylindrical to obconic, strigose, by its fleshy tap root bearing a low For species identification the and with 1–2 ribs per side. The of narrow, 3-nerved leaves, accounts in Barkley et al. (2006) and pappus consists of 1–2 rows of and solitary flowerheads with white Semple et al. (2002) are helpful, but barbellate bristles. ray florets. it is not easy. A single plant can Galatella sedifolia (syn. Aster change shape completely during sedifolius) is in cultivation, and plants Symphyotrichum the growing season, involucral from the eastern Mediterranean­ are This is the largest genus that has been shape can change between early and sometimes grown as G. punctata (syn. split off from Aster. It has about 90 late flowering, and the shape and Aster punctatus) (Grierson 1975, Semple species distributed throughout array of flowerheads can vary hugely et al. 2002). Further study has America, with one, S. ciliatum, also due to environmental factors. This, upheld the treatment of Merxmüller native to Eurasia. The genus contains combined with selection and hybrid­ (1976) who treated the European the Michaelmas daisies S. novi-belgii ization in cultivation, makes the taxa as subspecies of A. sedifolius, but (syn. Aster novi-belgii) and S. novae- variation difficult to characterize. included A. punctatus within A. sedi­ angliae (syn. Aster novae-angliae), as For identifying cultivated plants it is folius subsp. sedifolius. Greuter (2003) well as small-flowered asters such usually easier to use colour illustrat­ has provided new names in Galatella as S. ericoides (syn. Aster ericoides) and ions, such as those in Picton (2004). sedifolia as subspecies,­ but with S. lateriflorum (syn. Aster lateriflorus). Older, -based cultivar names, G. punctata as a of G. sedifolia The flowerheads, each with 12–35 of which there are very few, as well subsp. sedifolia. The situation in fertile ray florets, are arranged in as species epithets previously used in Turkey is summarized by Hamzaoğlu panicles of varying shapes. Each Aster (masculine) have to be modified et al. (2013) with updated nomenclat­ flowerhead has 20–84 involucral to agree with Symphyotrichum ure and an identification key. bracts, usually in 4–6 series, the bracts (neuter), hence A. oblongifolius Galatella and its rayless near being linear to deltoid or lanceolate becomes S. oblongifolium, and so on.

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Tripolium Conclusion The single species in this genus, This brief survey introduces a few T. pannonicum (sea aster, previously of the many name changes that are A. tripolium) is easily distinguished by the result of ongoing research in its succulent leaves. It is a biennial or Asteraceae taxonomy. annual of salt marshes, and thereby More changes are anticipated useful in some coastal gardens. among other large, horticulturally significant genera including Xanthisma and Senecio. Those who wish to read This genus of 17 North American more on the subject and gain a species is represented in cultivation detailed overview of the by an alpine subshrub, X. coloradoense. should seek out Funk et al. (2009). It has solitary flowerheads borne Mike Sleigh / RHS Mike over a rosette of oblanceolate, Julian Shaw is a botanist working Under their new names we have Galatella sedifolia (far left), Symphyotrichum novi-belgii (left) and serrate leaves. These have 20–35, in the RHS Science Department as Symphyotrichum novae-angliae (above) pink to purple ray florets. a registrar of plant names.

references Barkley, TM, Brouillet, L & Hamzaoğlu, E, Koç, M & Budak, Ü & Valentine, DH (eds.) Flora Europaea. Strother, JL (eds) (2006) Asteraceae. (2013) Galatella anatolica sp. nov. Volume 4. Cambridge University Press, In: Flora of North America Editorial (Asteraceae: Astereae) from Osmaniye, Cambridge Committee (eds) Flora of North America Turkey. Nordic J. Bot. 31: 87–98 Picton, P (2004) The Gardener’s Guide North of Mexico, Vols. 19–21. Oxford Heywood, VH (1978) Flowering Plants to Growing Asters. David & Charles, University Press, & Oxford of the World. Oxford University Press, Devon, & Timber Press, Bremer, K (1994) Asteraceae: Oxford Semple, JC & Brouillet, L (1980) and Classification. Timber Press, Oregon Heywood, VH, Brummitt, RK, Chromosome numbers and satellite Brouillet, L, Allen, GA, Semple, JC Culham, A & Seberg, O (2007) chromosome morphology in Aster and & Ito, M (2001). ITS phylogeny of Families of the World. Lasallea. Amer. J. Bot. 67(7): 1027–1039 North American asters (Asteraceae: Royal Botanic Gardens, Kew Semple, JC, Heard, SB & Brouillet, L Astereae). 2001 Abstracts: 1 Iwatsuki, K, Yamazaki, T, (2002) Cultivated and native asters of (abstract 412) Boufford, DE & Ohba, H (eds) . Univ. Waterloo Biol. Ser. 41: Cullen, J et al. (eds) (2000) The Euro­ (1995) Flora of Japan. Volume 3b. 1–134 pean Garden Flora. Vol VI. Cambridge Kodansha, Tokyo Shi, Z et al. (eds) (2011) Asteraceae. In: University Press, Cambridge Jones, AG (1980) Data on Flora of China Editorial Committee Fiz, O, Valcárcel, V & Vargas, P chromosome numbers in Aster (eds) Flora of China. Vol. 20. Science (2002) Phylogenetic position of (Asteraceae), with comments on the Press, Beijing, and Missouri Botanical Mediterranean Astereae and character status and relationships of certain Garden Press, St Louis evolution of daisies (Bellis, Asteraceae) North American species. Brittonia 32: Willis, JC (1973) A Dictionary of the inferred from nDNA ITS sequences. 240–261 Flowering Plants and Ferns. 8th edn. Molec. Phylogen. Evol. 25: 151–171 Jones, AG (1983) Generic concepts Cambridge University Press, Cambridge Funk, VA, Susanna, A, Stuessy, TF of Aster (Asteraceae): A comparison of Xiang, C-S & Semple, JC (1996) & Bayer, RJ (eds.) (2009) Systematics, cladistics, phonetic, and cytological Molecular systematic study of Aster Evolution and Biogeography of approaches. Syst. Bot. 8(3): 71–84 sensu lato and related genera based on Compositae. IAPT, Vienna Li, W-P, Yang, F-S, Jivkova, T & chloroplast DNA restriction site Greuter, W (2003) The Euro+Med Tin, G-S (2012) Phylogenetic analyses and mainly North American treatment of Astereae (Compositae) – relationships and generic delimitation taxa. In: Hind, DJN & Beentje, H (eds.) generic concepts and required new of Eurasian Aster (Aster: Astereae) Compositae: Systematics. Royal Botanic names. Willdenowia 33: 45–47 inferred from ITS, ETS, and trnL-F Gardens, Kew Grierson, AJ (1964) A revision of the sequence data. Ann. Bot. 109: 1341–1357 Yatskievych, G (2004, published asters of the Himalayan area. Notes Roy. Mabberley, DJ (2008) Mabberley’s 2005) How faster to master the Aster Bot. Gard. Edinburgh 26(1): 67–163 Plant-Book. 3rd edn. Cambridge disaster: A primer on the changing Grierson, AJC (1975) Galatella. In: University Press, Cambridge nomenclature of Missouri asters. Davis, PH (ed.) . Vol. 5. Merxmüller, H (1976) Aster. In: Missouriensis 25: 26–31 Edinburgh University Press, Edinburgh Tutin, TG, Heywood, VH, Burges, NA

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