In this installment of Jimi’s plants, I decided to look at a group of his favorites from the Aster family, one of the largest plant families, in terms of number of species, in the world and the most recently evolved…bear in mind that ‘recent’ in evolutionary terms can still be millions of years ago. All of us are familiar with the classic aster or sunflower form of inflorescence that occurs on many, but far from all, of these species. We’ve all grown many of these in our gardens and recognize many species as local and regional natives. As ‘common’ as many of us may view this family to be, it contains a great many species with both beautiful and unique characteristics for use in our gardens.
Inulanthera dregeana (calva subsumed)
Inulanthera is an entirely new genus for me. I don’t recall ever seeing it before, but the two ‘roots’ that have been joined together to make this genus name…I do know. Inula are in the Aster family. Several of them are relatively common garden plants. Inula magnifica is a coarse textured, large, herbaceous perennial, that grows 6′-8′ tall, typically used in the back of large deep sunny borders. I. racemosa ‘Sonnenspeer’ is another coarse tall grower to 6′. I. hookeri, is a dense slowly spreading perennial to about 4′. There flowers take the typical Aster composite form we expect from this group, with a ‘head’ or ‘capitulum’ of disk florets crowded together and surrounded by a ring of ray florets forming what botanists call a ‘radiate’ head. In many genera in this family the central head is domed sometimes to the extent that it forms a cone, but Inula have flat heads. Each floret is an independent, complete, flower with its individual sex organs, joined together at the base of their ovary to what is termed a ‘receptacle’, whose form is echoed and amplified by the overall form of head. On a ‘radiate’ head the ray florets differ from disk florets in that they have a ligule, which is formed by a fusion of 3, sometimes two, of the floret’s 5 petals. The remaining petals are generally greatly reduced. These singular ligules of each ray floret combine to give the head the appearance of having individual marginal petals. There can be a hundred or more disk and ray flowers in a head, each with their own ovary that produce a single seed. Think of the large domed heads of Sunflowers crowded with seed each attached singularly from an end to the receptacle. In some species, in other genera of this family, the florets are reduced down to one, but they still have the same structure and are attached to a receptacle. The ‘receptacle’ is a more modern structure and occurs in no other plant family…so far. As this is one of the largest families in the plant world there are a great many with this particular radiate head structure to complicate ID’ing. The family includes around 33,000 species currently, of which these three plants, while not particularly common, are available on the west coast from Digging Dog Nursery in Albion, CA.
If you watch carefully you will notice that the florets don’t bloom all at once. The disk florets will tend to begin first at their perimeter and work their way towards the center, each one first presenting their combined style/stamen structure in which the female style emerges from a tube of fused stamen, dehiscing or releasing their pollen in a sort of slow wave to the head’s center. The crowded little disk florets also have 5, abbreviated, petals giving the center disk its compact, dense, sun like appearance. The species of genus Inulanthera have discoid heads…like our too common Garden Tansy, Tanacetum, and so do not have any ligulate ray florets. Their heads present like simple flattened ‘buttons’. Like genus Inula, their species have round flat receptacles that give their heads their characteristic shape, but it is not the ‘heads’ of these two genera that share a commonality beyond being in the same family, but a defining and more particular characteristic of their anthers. Just to further complicate/explain the floral heads of the many genera in this family, other heads can be entirely composed of ray florets, each with their own ligule. These are called liguliflorus…of course they are. Others have ‘disciform’ heads, looking much the same as the button like discoid group, only their marginal florets are sterile female ray florets…that have much reduced ligules. And, as if this weren’t complicated enough, there are also ‘radiant’ heads, with a discoid head having a peripheral ring of flowers each with much enlarged, often bilateral, or ‘split’, corollas. Perhaps this will help…or not! The details of this can make you crazy, at least until you become more familiar with the terms. Within these different head structures there is variation. Genus Cirsium, which includes many of the species we commonly call Thistles, is in this family and has heads composed entirely of disk flowers…their corollas are comprised of the usual 5 fused petals, but are considerably longer and, emerging out of each one of these, are elongated anther tubes giving the floral head a fuzzy ‘top-knot’! Inulanthera is a genus of ten species in the Aster family, seven of which are endemic to South Africa, primarily in KwaZulu-Natal. One species each of the remaining species can be found in nearby Angola, Madagascar and Zimbabwe. Some botanists have suggested that I. calva should be included within I. dregeana. The Aster family is a big player in the entire Cape region. Gardeners are likely most familiar with the group of several genera whose species are commonly called African Daisies, including Osteospermum, Arctotis, Dimorphotheca and Gazania while others may include Gerbera with them. There are many other member genera as well including species of Senecio, like Blue Chalk Sticks.
In the case of this genus, the root ‘anthera’ refers to a flower’s anther, theirs being conspicuously ‘tailed’, if you look close enough. The namer of this genus thought the anthers on these two genera were similar. Very often the key characteristics with which we separate species are so tiny, to the point of being insignificant to the casual observer, but unique they are, both in morphology, appearance, and genetics. Inula spp. are primarily Mediterranean having evolved separately, in the northern hemisphere, while Inulanthera developed separately.
It is the science of this plant, its details, that I find appealing and I am grateful for the botanists who do the work that brings it to us. For me it deepens the sense of awe and wonder I have for life. I found this research article on Inulanthera spp. totally readable and understandable, on line. Initially I was a little unenthusiastic about this genera and I might have passed it up. The article ‘convinced’ me to look more closely. I h’ve had a strong interest in South African plants, having grown only a tiny fraction of the region’s incredibly abundant and diverse endemic flora. Several genera have semi-permanent ‘homes’ in my garden including two Melianthus spp., several Eucomis spp. and cultivars, a couple Restio, Berkheya, etc. as well as several I really shouldn’t attempt like the small tree, Greyia sutherlandia. We don’t all like every plant that others grow, we have our preferences, and this plant with its woody base and herbaceous top growth doesn’t really do it for me.
I’m not sure how tolerant of our conditions Inulanthera dregeana is. Above is the map showing its natural range with dots locating known populations. It shows elevation as well. Some of the mountains of the eastern Cape are quite tall, the Drakensbergs, forming part of the border with Lesotho, the independent, land-locked kingdom surrounded by South Africa, and provide a definite westward limit to this species, which tends to occur below 1,200m, on grass lands and along forested edges. The species does spread westward along the south coast while being restricted from moving very far north there by the Kammanassie Mountains. Included in this particular area is the Kammanassie Nature Reserve which was created to protect this portion of the Cape Floristic Province, an area with a fantastically high diversity and rate of plant endemism, species that naturally occur nowhere else in the world than on this quite small patch of ground. In this area more eastern plants, like this Inulanthera, rub ‘plant shoulders’ with western endemics, where Fynbos, ‘fine bush’, and grassland come together. There is no other place in the world with such a unique flora making plants like this all the more alluring to geeks like me. The bulk of South Africa is quite dry, semi-arid to desert, including most of the western areas, the Karoo and Kalahari, along with the Southwest and South Cape, receiving what little precipitation they get in the winter months which can vary widely with drought years common. These areas are supportive more of succulent and shrub steppe vegetation than the moister grasslands found in the Eastern Cape. Toward the north end of the ‘arc’ shown on the map, including Pretoria and Johannesburg, the region experiences more of a bi-modal rain season, winter, then summer, shifting to a more distinctly summer wet pattern as you move along it to the south then shifting toward a more winter wet/oceanic pattern as you move westerly along the coast. The KwaZulu-Natal lies in the ‘lower belly’ of the arc and is primarily a summer rainfall area. The Drakensberg Mountains back much of this region to the west and serves as a guide and barrier to rainfall. This species is found primarily in grassland communities whose locations are also determined in part by the richer soils that underlie them. Likelihood of finding the plant communities this lives in increase with increasing rainfall especially when it occurs during the growing season and as you move from younger, poorer soils toward areas of richer soils. The natural growing range of this plant extends north and south across most of the eastern part of the country, from around 33.5ºS to just north of 23.5ºS, the Tropic of Capricorn, placing the country firmly in the sub-tropical band. Again, like any plant rare in cultivation, finding this might be the biggest challenge. When all attempts to find it from nurseries here failed, i went to the source for all plants out of South Africa, Silverhill Seeds with their incredible list. I’ve not bought from them before, but seed is generally the easiest way to get and grow South many African plants, or those from any other region for that matter, that are not already in nursery production here. The species of this genera are not even commonly available there from their local nursery producers, because like most gardeners everywhere tastes and demand tend to lean more toward the exotic and mainstream European traditions. So if you want this, first you’ll have to find a seed source and that might require first contacting South African native plant groups. In cases where plants are under pressure and threatened, which this is not, even the sale of their seed can add more pressure to wild populations through the action of less than scrupulous collectors, whereas when seeds are collected from nursery grown plants this is averted. Additionally there is much less chance of importing weeds and diseases when trading in seed as well, even though transporting live plants across borders often involves washing the soil away from the roots before packing and shipping them. Plants noted as Threatened and Endangered on the ICUN Red List may have restrictions on the exportation of seeds collected in the wild as the practice contributes to the threat to the wild population. Silverhill Seeds most current listing offers only Inula leucoclada, a species with a more restricted range from the grasslands of the coastal hills of the far Eastern Cape. Interestingly it is the only species to have adapted to fire by germinating from seed alone. Each plant forms a single unbranched stem. All of the others can resprout from their base after a fire and have a tendency to sucker.
South African on-line botanical resources:
The South African National Botanical Institute has this site on which you can search for any native species and it will produce a map of all the recorded sites on which participants have found it. The map shows topography as well so you can see something of the terrain on which it typically grows. They have also created an extensive and exhaustive map of the 435 unique
plant communities across the country in GIS format, it is very data intensive and slow to load…that I am still trying to figure out….The content of plant communities and their spatial relationships can provide gardeners with important hints/information toward how to best/successfully grow a plant. The concept of matrix planting, creating garden compositions that are supportive of its members and has a resistance to weeds by filling niches. For weather nerds this pdf describes the ITCZ, or InterTropical Convergence Zone, which wraps around the Earth’s equator producing the broad band of humid/rainy conditions that influence so much of the Earth’s weather. This band moves variably north and south with the seasons and, in the case of South Africa, in the adjacent sub-topics, strongly influences the weather in the summer wet/humid area around Johannesburg and Pretoria, which is the northern limit of Inulanthera dregeana, while keeping much of the country so dry or effected by trade winds and its coastal position.
This is a ‘cool’ plant, literally and figuratively, the kind of plant that could even be worth moving for, to find conditions more supportive of its growth. I had only seen this in pictures before seeing it grown in a friends garden in Victoria…and was devastated to learn that down south in Portland we are likely too hot to be successful with it, a problem I’ve encountered with other attractive plants I’ve ‘discovered’ from the same region of origin, a problem similar to that for many plants from cloud forest regions. For you Puget Sounders, though, as long as you are well within the Sound’s maritime influence, this could be a no brainer…you should be growing it. Here in Portland we generally get too hot in our summers and this is one of those New Zealanders that abhor heat! Celmisia is a genus of 79 species belonging to the Aster family, all of which are southern hemisphere plants, 60 of which are endemic to New Zealand, the rest are endemic to mountain areas of SE Australia, Tasmania and a few small sub-antarctic islands. The Asteraceae occur on every continent other than Antarctica. This genus developed after the breakup of Gondwana when Australasia had already separated and so do not appear on any of its ‘sister’ continents. Celmisia semicordata is the largest growing species of the genus forming a robust rosette or clump of stiff leathery silvery-green, sword-shaped, 30-60 cm long by 4-10 cm wide leaves. The undersurface of the leaves is covered in a silvery fluffy tomentum, the upper is covered by a thin pellicle, or ‘skin’ that gives it its ‘metallic’ sheen. The flowers are held in the common daisy type, radiate head, composed of disk and ray florets. Each plant possesses only male or female florets. Obviously, you must have one of each to produce viable seed.
This species occurs commonly on the South Island from near the coast well into sub-alpine areas and is in fact most common at some altitude, occurring most frequently between about 2,000′ and 4,600′. The South Island is predominately mild-temperate/maritime with an average low somewhat above ours, with most of the coast and uplands ranging from the equivalent of our zn 8b to 9a-9b. Some species can be found well up in the mountains where they can spend considerable time under winter snow. It is interesting to note that some sources rate this species as cold hardy into zn 6! New Zealand’s Southern Alps form a jagged spine for most of the island’s length, a landscape that is colder and more harsh as is typical of such rugged, thin soiled, high country. Overall, summer highs on the South Island tend to average from 6º-16ºF cooler than ours. This genus, as a whole, is one of those that will collapse during sustained periods above 90ºF. This shouldn’t be that surprising to us as plants native to our own sub-alpine and alpine areas often suffer with our mild conditions on or near the Valley floor. With our locally increasing daily summer high temps Celmisia may be nigh impossible to grow here in Portland, having had 31 days over 90º this last summer.
The American Horticultural Society has produced a map that delineates ‘heat zones’ which looks at the annual number of days that high temps reach 86ºF and higher, the temperature at which many plants begin to suffer. These were created before using data through ’95 so they don’t show our recent upward trend. The average for Portland, has historically been 11 days hitting 90-degrees or better. Since 2000, the annual number of these has jumped to 15 days. Since 2014, the average is 22 days. Now we’ve just had 31….In climate terms this is radical and abrupt. Scientist don’t see this as a random fluctuation, they see it as the new norm and such changes can have dire consequences especially for plants already living at the margins of their heat tolerance. Increasing temperatures also have the effect of increasing the evapo-transpiration rate, increasing all plants’ use of water over a given period and our summers are already ‘dry’. Our daily summer lows are increasing as well. While some gardeners may embrace this change and grow plants that were previously more difficult because we were too cool, and I am among these ‘zonal deniers’, our growing season typically too short, our nights too cool, are finding that now, many of these plants perform ‘better’ for us. For other plants, like Celmisia spp., our warming temperatures are becoming more of a limiting factor as it will be for many of our native plants.
Trying to grow plants that can’t tolerate such heat is a bit of a fool’s errand just as it is more than a bit naive to not make the changes one can that contribute to the problem. For gardeners along the coast, however, this could be just what the collector of the novel is looking for. Another difficulty with these, though more easily overcome, is that they don’t tolerate dry soil. They demand a more steady source of moisture. Some species are in fact bog plants. Most are commonly found in what is described as snow-tussock grassland, herbfields and open subalpine scrub in New Zealand. A relative few can be found on the North Island with its even milder minimum temperatures and fewer still in drier regions along the eastern coast. Most of these requirements can be accommodated by careful siting, perhaps on north facing slopes, irrigation, soil mixes and the containers themselves. It is difficult to overcome temperatures that are too warm, however.
Celmisia are grown readily from seed. They might almost be considered ruderal species in New Zealand as many commonly move on to disturbed sites within its range. C. semicordata is one of the more widespread species and shows considerable variation in leaf and form. As you might expect from this proclivity and the relatively small human population there, this is considered ‘unthreatened’, secure in terms of extinction. The seed is best sown when fresh. They require 4-6 weeks of cold stratification for germination and may benefit from smoke treatment. They may also take some time to germinate, leave them for two years before you give up on them. Several species are grown by members of alpine and rock garden societies especially in the UK. Some growers contend that Celmisia allanii, is more tolerant of typical garden conditions and recommend it to those new to this genus. Cuttings can be taken after flowering, stripping declining and dead leaves from the lower stems before plunging them into mix that is kept moist. This is as would be expected with a plant that is a mat former. This may be less successful with those species that are more ‘singular’ in habit.(?)
Celmisia semicordata is considered by many to be the most garden worthy of them all for its showy foliage ranging from silver to gold . The several species all form mat or cushion type plants, low, dense and compact. Some are considered sub-shrubs, with a low woody base while others are all herbaceous. All are evergreen and all produce the white daisy type flowers, often in profusion. See this article on Celmisia allanii. Many of the species are truly alpines, some are residents of high bogs, some tend to occur on the drier eastern side of South Island. Their foliages vary in size and shape, but all have the common pellicle, a thin ‘skin’ over the leaf which gives it its particular metallic finish, the color of the epidermis below showing through. Astellia chathamica, from the nearby Chatham Islands, also has a pellicle, which gives its channeled leaves their particular silvery finish. See this article from the Alpine Garden Society for a quick review of the genus!
Celmesia s. ‘David Shackleton’ is an old clone that some say is difficult to come by today and they attribute that to the fact that the clone has weakened after so many years of being asexually propagated. Some suggest that what is needed is for new selections to be made of seed grown plants from the wild. Genetic diversity and vigor are best maintained through sexual reproduction and seed grown plants. Our human tendency to select from wild plants those with the characteristics we like does not necessarily provide us with the ‘best’ plants over the long term….As long as wild populations are healthy and their genetic diversity is protected we can always tap back into it as needed or desired. Of course as those wild populations decline our choices become more limited. For now, at least, this does not seem to be an issue with Celmisia spp. Two of the richer areas in terms of diversity are the Mt. Arthur area near Nelson, at the north of the South Island, and the Arthur’s Pass area some 200 miles southwest in the mountains west of Christchurch.
Senecio candidans (?) ‘Angel Wings’
Disclaimer here: this is not one of Jimi’s plants…however, I saw it grown in several of the gardens during the study weekend, and, it is a beautiful thing! I seem to be a bit outside the loop, because this one caught me completely unawares. Senecio is one of the largest genera in the plant world containing some 1,250 different species, but this is a ‘soft’ number, because scientists, even utilizing genetic material, are having trouble sorting it out. Its distribution is nearly worldwide, occurring in all five mediterranean regions of the world, the Mediterranean itself, western Australia, the west coasts of North and South America and the southern Cape of Africa as well as many mountainous regions of the world, including tropical. There appear to be no shared structures that define these alone as a group separate from all other genera…despite the common complaint that one can tell a Senecio by its ugly flowers, a pejorative I don’t agree with. This problem does cause botanists difficulties, but this plant, on its own is remarkable. Remarkable also is its acension in the worldwide marketplace. Somebody appears to have their marketing act very together! (One source suggested that this isn’t a particularly unique or distinctive selection of the species, and that this plant is typical of the type! ‘Angel Wings’ was simply a name selected to sell more plants.)
After being developed in Chile, the labs got to work with perfecting a tissue culture lab protocol and got ‘geared up’. In January of ’17 this was presented to the huge trade show in Essen, Germany, now it is available around the world. My understanding is that Concept Plants holds the international license for this. There are lots of plants with superior aesthetic qualities that never make it to market or are only ever available from limited specialty growers, often because they are difficult to propagate, not suitable for tissue culture and so are hard to produce in the necessary numbers for a ‘grand’ unveiling… Slow to increase plants aren’t amenable to such promotions….Many plants simply suffer from a lack of marketing dollars. Business is business after all and suppliers of any consumer good does what it can to maximize its investment. This Senecio has the looks, promotional dollars and the production possibilities that can ensure that it could make a grand entrance. This doesn’t take away from the plant…it is just another example of fashion and the economic machine shaping the market and demand.
There are a number of websites, US and European, extolling the virtues of this plant and I don’t think I need to try to out do what they’ve already done. Two regional suppliers should suffice here: Crocus in the UK and Annie’s Annuals in California.
When we look at this plant’s name we begin to run into some confusion and trouble. Senecio candicans is a species that originated in India…though S. c. ‘Angel Wings’, with the unattractive patented name of, ‘Senaw’, was developed by Floricultura Novazel S.A. from Lampa, Santiago, Chile, selected from plants growing in the Falkland Islands and the southern tip of South America. The two plants, the species from India and this one, are in fact different species. This specific name, candicans, goes with the earlier named plant from India. When the plant from the Falklands was originally described in 1794 it was given the name, Cacalia candicans. It was later reclassified as a Senecio and, in order to avoid confusion, was assigned the specific epithet of candidans, which some assumed was an error and ‘corrected’ to the incorrect candicans! The nursery industry has apparently chosen the incorrect name to use in their marketing efforts. Again, the correct name is Senecio candidans! (Source) Further confusion was caused when, the RHS Dictionary of Gardening (Huxley & Griffiths, 1992) and the RHS Plant Finder (Philip & Lord, 1994 and onwards), linked S. candicans to S. cineraria, a Mediterranean species to which it is evidently unrelated. This confusion appears to have arisen from the similarly named S. candidus, considered by Flora Europaea (Tutin et al., 1976) as a synonym of S.bicolor subsp. nebrodensis but now treated as a distinct species by the Euro-Med Project under the name Jacobaea candida, what we commonly refer to as Dusty Miller….Glad that’s all cleared up! Names!!!
The species is normally found on exposed dunes of the Falklands and Tierra del Fuego. These are sandy low nutrient sites, probably with considerable salt exposure, along with regular steady to higher wind. At between 51º and 52º S the islands are at a latitude comparable to London, but without the warming influence of the Gulf Current and, with their proximity to Antarctica, conditions are considerably cooler. It was a bit of a surprise to find that the annual precipitation averages around 23″, varying from about 14″ on the drier west side to 35″ on the wetter eastern side. The South American Andes interrupt much of the potential rainfall. There is no dry season. Annually temperatures range between 23º- 75ºF. This is a maritime sub-arctic climate and the Islands generally lie in the area of the Antarctic Convergence Zone where cold polar water, moving north into the warmer south Atlantic waters mixes, creating an upwelling current very rich in sea life, a band 20-30 miles across, distinct from the ocean life north and south of it, which also has a stabilizing effect on the Islands’ climate. I suspect this may be another difficult plant for me in ‘hot’ Portland for very similar reasons as the Celmisia I discuss above. I’ve read of gardeners planting these out, or in pots, looking beautiful in the Spring and early Summer, only to crap out when serious heat settles in during July and August. Some have speculated that the problem may be exacerbated by an increased frequency of irrigation, especially in heavier soils. Still, in maritime climates, like the Seattle area, with their more moderate temperatures, I would expect that this will likely be fine. Perhaps an open northerly slope with good air circulation just off the Sound! I’m also curious if by growing these in the soil in more marginal areas that the soil may serve as a buffer cooling the plants slightly better as compared to those in pots surrounded by what they might consider to be ‘superheated’ air. What say you Seattlites? I did not run out and buy this plant when I got home after the Study Weekend. Some, I spoke to in Seattle, expressed some caution wondering if it might lack the necessary vigor when grown here and worried that their experience would repeat theirs with Stachys ‘Bella Grigio’, another plant that has suffered due in part to problems with its name and being misidentified. In fact there are striking parallels between these two different species. See this blog article from the Laidback Gardener! This plant’s name is actually, Senecio niveoaureus ‘Bello Grigio’ and, with its very similar ‘color’ and softness, could fill a similar role in our gardens. It is from the paramo, or high alpine country of the Andes in Colombia and Ecuador ranging between 9,000′-14,000′ with its high year round humidity due to the Intertropical Convergence Zone and the Andes which together produce around 79″ of rain annually. This is a spare landscape above tree line. S.n. ‘Bello Grigio’ was initially marketed as an annual or tender perennial prompting many to provide conditions it actually didn’t want! At least some of us tend to think drought tolerant, heat resistant, when we see white, tomentose, foliage on plants like this, when in reality they aren’t arid or desert plants at all. This characteristic covering of their epidermis, while not common, occurs on some wetter region plants like the Himalayan Potentilla gelida with its summer wet/monsoonal climate. Such a covering offers some protection to these high alpine plants beyond its ability to slow desiccation.
Senecio sometimes get a bad rap. Yes, some are common weeds here, like Senecio vulgaris, the annual Common Groundsel, and at least one, is on the Oregon State list of noxious weeds, Senecio jacobea, Tansy Ragwort, but many of them make amazing aesthetic contributions as specimen here in the PNW…as long as we pay attention to their requirements. I frequently grow plants like Senecio mandraliscae, now known as S. serpens, but also having spent time under several other names, Senecio confusus, apparently now suffering under the unwieldy name of Pseudogynoxys chenipodioides and other oddities like Senecio cristobalensis. Judge each plant on its own merit.
I am most familiar with the species of Sonchus that are weeds. I have pulled more than my share of Annual and Prickly Sow Thistle, Sonchus oleraceus and S. asper, but like many genera Sonchus contains several plants of horticultural merit. Most Sonchus are annual species, a few are perennial and fewer still are ‘woody’ species all of which occur on the Canary Islands alone, like Sonchus palmensis.
There are 19 different species of ‘woody’ Sonchus on the Canary archipelago. Five of the seven islands contain at least one of these species as a local endemic. Fuerteventura is around 60 miles from Morocco, the islands are spread along a line westerly, each having arisen volcanically, the most westerly, El Hierro, forming less than a million years ago, Fuerteventura, almost 21 million. Genetic researchers believe that based on their studies, these woody Sonchus species are all descendants of a single colonization event which then spread from island to island in a process of speciation and radiation. Genetically, the plants are very close especially when compared to other flowering plant genera and this is consistent with the isolation found on smaller islands around the world. It is interesting to note that eight other species are also closely related, but are within other genera. A few of these can be found on the island of Madeira and the Cape Verde Islands. All of these have taken a very similar evolutionary pathway, though their forms and the environment within which they naturally occur, are sometimes quite different. This group forms what is recognized as the Woody Sonchus Alliance. Such alliances are not unusual on isolated islands. These remind me of the ‘woody’ Tree Lobelias that are endemic to the Hawaiian Islands, an alliance of 125 species including several genera. There, Lobelia are thought to be amongst the earlier plant arrivals and through a similar process of speciation and radiation evolved into the unique and diverse species we see today, in their cases, several of which are threatened. Sonchus palmensis is endemic to the the single island of La Palma, which at only 1.5 Mya is the second youngest of the seven Canaries. Three other members of the Alliance can be found there. It occurs around the entire island growing at elevations up to 3,300′, often on quite steeply sloping and rocky terrain, though most commonly found on the eastern side. Pictures will show this growing out of rock piles suggesting that they will want very good drainage. Because they are quite common on La Palma they are listed as ‘of least concern’ by the IUCN. The stems grow up to 6′ tall, branching irregularly on mostly bare stems. The foliage is very similar in form to that found growing around the rosette of our local annual Sow Thistle, on this species forming leaves closely attached to one another near the terminals of each branch, giving the plants what some would term their gawky appearance and others would describe as ‘Dr. Seussian’. At flowering, a many branched inflorescence forms at the terminal carrying typical Asteraceae heads often described as ‘Dandelion like’, each floret, including all of the center disk florets, being ligulate with their two fused elongated petals and three diminished ones.
The climate on La Palma is very mild, sub-tropical oceanic, with remarkably consistent average temperatures around the year. La Palma the youngest, most westerly island, is less influenced by the heat of the African continent than are the other, nearer islands. It also has very little flat plateau area and consequently is wetter across the majority of its surface than the other islands. Temperatures tend to cool with elevation, the warm moist air rising against the mountain sides and cooling, the moisture condensing and falling as rain. Broad flatter terrain tends to warm more and clouds can sail over. Overall this is the ‘greenest’ of the seven islands. Keep in mind that while most of the rain is received in winter months, fog and heavy clouds often form around the mountains during summer, both cooling and adding moisture through condensation. This can be grown well outside in the Bay Area with its moderated summers. Sonchus, as a group, will grow best in full sun and are tolerant of summer drought conditions though S. palmensis may be more dependent on regular water than the other species. In California, Sonchus canariensis, is considered to be drought tolerant. Understand that this latter species is native to Gran Canaria and Tenerife, both more easterly, warmer and drier. These are considered to be hardy to zn 9b, down to 25ºF, some suggested colder, as one might expect coming from the Canary Islands where it can rub plant ‘shoulders’ with other natives like several Aeonium spp., Echium wildpretii and several Euphorbia spp. How many zn 9b plants does one need in a zn 8b garden? Well, for me it depends on its gifts, what it offers the garden and how it measures up to the other plants I’m already growing that require me go the extra mile. This plant brings a lot to the garden table. For now it goes into the queue. Unlike the two previous plants this will take our heat. I can picture growing it successfully on my front porch in a large pot where it will be shaded from the hottest part of the day, late afternoon…and it goes without saying, in a well drained mix with regular summer water! It would add a touch of humor to my xeric front garden with its strong architectural form looming from on high.