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Jeremy Bartlett's LET IT GROW blog

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"People from a planet without flowers would think we must be mad with joy the whole time to have such things about us." - Iris Murdoch

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Beaked Hawk’s-beard, Crepis vesicaria

Jeremy Bartlett's LET IT GROW blog Posted on 15 May, 2024 by Jeremy Bartlett16 May, 2024

Beaked Hawk’s-beard, Crepis vesicaria, is in flower right now, in and around Norwich, its bright yellow flowers livening up grass verges and path edges.

I pass Beaked Hawk’s-beard on grass verges when I walk to the local shops. On Monday we found it by a gravel path on the Yare Valley Walk on the western edge of Norwich. Last week we cycled past a nice patch of it at Taverham when crossed the Norwich’s Northern Distributor Road (NDR) on the Marriott’s Way cycle path.

Beaked Hawksbeard, Crepis vesicaria

Beaked Hawk’s-beard, Crepis vesicaria. Marriott’s Way bridge, Taverham. 9th May 2024.

In the southern half of the British Isles Crepis vesicaria is “the earliest, leafy-stemmed branched dandelion-type to come into flower, very conspicuously, on May roadsides” (note 1). You can find it in flower in the British Isles from May to July.

Considering its abundance in southern Britain, you may be surprised to discover that Beaked Hawk’s-beard is a neophyte, a non-native plant introduced to the British Isles since 1492.

Crepis vesicaria was first recorded in Kent in 1713. It spread rapidly and by 1896 it had reached the west coast of Ireland. It continues to spread and is now well-established in north-east England and spreading in western England, Wales and Ireland. It has a limited distribution in Scotland – so far – perhaps limited by climate.

Crepis vesicaria is a member of the Daisy family, Asteraceae (formerly known as the Compositae) and each flower head is a composite structure consisting of lots of individual small flowers (florets) (note 2).

Beaked Hawk’s-beard is usually a biennial, flowering in its second year, but it does occasionally grow as an annual or perennial. In its first year it produces stalked, deeply lobed basal leaves covered in light down, which persist over winter. In its second year the plant sends up stems clasped by narrow leaves, which branch into multiple flowering stems, each topped with a yellow dandelion-type flower head. The outer ray florets of the flower have an orange-red stripe on the underside (note 3). If cut, the stems bleed bluish-white sap (note 1).

After flowering, Beaked Hawk’s-beard sets seed. Crepis vesicaria seeds have a narrow, elongated “beak” at the top, between the seed and the tuft of silky white hairs (pappus) that serves to distribute the seed in the wind. Hence the name “Beaked Hawk’s-beard” (sometimes spelt “Beaked Hawksbeard”).

There are great photos of Beaked Hawksbeard on the Wild Flower Finder website and Mike Crewe’s Flora of East Anglia has a page of Hawkweeds, Hawk’s-beards & Allies which are useful for comparing Crepis vesicaria with its relatives.

Beaked Hawksbeard, Crepis vesicaria

Beaked Hawk’s-beard, Crepis vesicaria. On a pathside in Norwich, 13th May 2024.

In the British Isles, Beaked Hawk’s-beard mainly grows in disturbed sites: on the verges of paths, tracks and roads, on railway banks, arable margins, set-aside, pavements, gardens, allotments, in waste places and in rough grassland, meadows, lawns and old pits.

Beaked Hawk’s-beard was introduced into Britain from the Mediterranean, probably as a contaminant of grass seed (note 4). It is a native of southern Europe, Turkey, and North Africa (Algeria, Morocco and Tunisia).

As well as the British Isles, Crepis vesicaria has been introduced into the United States (California, Connecticut, Hawaii, New York, North Carolina, Oregon and Pennsylvania), Canada (British Columbia) and Australia (South Australia and Victoria).

The Plants of the World Online website lists nine subspecies of Crepis vesicaria. Most British Beaked Hawk’s-beard plants are Crepis vesicaria subspecies taraxacifolia and have long beaks on all their achenes. But some plants from Cambridgeshire have outer achenes with very short beaks, provisionally making them subsp. stellata (note 5).

In the Norwich area, Beaked Hawk’s-beard is often attended by a solitary bee slightly smaller than a Honeybee, the Cat’s-ear Mining Bee, Andrena humilis.

Andrena humilis is widespread but very localised in southern and central Britain north to Cumbria and Norwich is one of its hotspots. It nests on heathland, coastal grassland, chalk downland and brownfield sites, as well as in large aggregations alongside bare footpaths. The adults forage on dandelions, Cat’s-ear, Mouse-ear Hawkweed and hawk’s-beards. Other bees also visit Beaked Hawk’s-beard flowers, such as species of Furrow Bees (Lasioglossum sp.).

Beaked Hawksbeard, Crepis vesicaria

Beaked Hawk’s-beard, Crepis vesicaria, with visiting Catsear Mining Bee, Andrena humilis.

The Plants For A Future website says that Beaked Hawk’s-beard leaves are edible and can be eaten in a salad but they have a bitter taste. I’m not tempted.

If you want to grow Beaked Hawk’s-beard in your garden it is very easy to grow from seed collected from wild plants. I did this one year but it didn’t establish in our densely planted, north-facing back garden. It should do well in a sunny site with some bare soil – perhaps too well.

Notes

Note 1 – “Harrap’s Wild Flowers: A Field Guide to the Wild Flowers of Britain & Ireland”, page 266. Simon Harrap (Bloomsbury, 2013). Dandelions and Coltsfoot come into flower earlier but their flowerheads are borne on single stems.

Note 2 – I have already written about some of its relatives, including Marsh Sowthistle (August 2023), Common Fleabane (July 2022) and Broad-leaved Ragwort (September 2021).

Note 3 – Beaked Hawk’s-beard close relative, Smooth Hawk’s-beard (Crepis capillaris), also has this stripe and multiple flowerheads but it is a daintier plant that flowers slightly later in the year.

Note 4 – From page 420,  “Alien Plants’” by Clive A. Stace and Michael J. Crawley (Harper Collins, 2015).

Note 5 – Page 756, “New Flora of the British Isles“ by Clive Stace, Fourth Edition, 2019. Stace’s Flora lists ten species of Crepis (Hawk’s-beards) in the British Isles.

Posted in Ornamental | Tagged Andrena humilis, Beaked Hawk's-beard, Beaked Hawksbeard, Cat's-ear Mining Bee, Crepis vesicaria

Thrift, Armeria maritima

Jeremy Bartlett's LET IT GROW blog Posted on 17 April, 2024 by Jeremy Bartlett17 April, 2024

I do like to be beside the seaside, particularly when Thrift, Armeria maritima, is in flower. Depending on where you are, this can be as early as late March and as late as early October, but Thrift’s peak flowering time In Britain is from May to July.

Thrift’s exuberant pink flowers have accompanied many of our holidays: on Isle of Wight cliffs, the Isles of Scilly, on Scottish coasts and islands and trips to East Anglian saltmarshes.

Thrift, Armeria maritima

Thrift, Armeria maritima, Isle of Wight, mid May 2016.

Also known as known as Sea Pink, Thrift is very much a plant of the seashore. It’s a member of the Plumbaginaceae (Leadwort family), along with Sea Lavender (Limonium), another coastal plant.

Thrift is a native perennial herb with compact evergreen cushions of needle-like leaves and long stems that bear spherical clusters of pink flowers. It grows on sea cliffs, stone walls, saltmarshes and stabilised shingle and its distribution in Britain follows the coastline. It is lovely as it flowers en masse, often made lovelier by a spectacular setting.

Thrift, Armeria maritima

Thrift, Armeria maritima, near Oban, late May 2018.

In East Anglia saltmarshes are often the best place to see it, though it grows on the cliff tops at Weybourne in North Norfolk. It can form extensive mats of foliage and on Annet in the Isles of Scilly, Geoffrey Grigson described walking across these as “a dream of walking on soft rubber that has squirted into flower” (note 1).

However, Armeria maritima is not just a seaside plant. It is very adaptable and can be found far from the sea too: on riverside shingle, windswept moss-heaths, stony flushes and on rocky mountain ledges, as high as 1,290 metres (4,200 feet) above sea level, on Britain’s fourth highest mountain, Cairn Toul in the Cairngorms.

Thrift, Armeria maritima

Thrift, Armeria maritima, island of Kerrera (near Oban), late May 2018.

Thrift tolerates the salt in sea water because it can excrete excess sodium and chloride ions via glands on the surface of its leaves. It can also can grow on old mine workings because it is able to deal with heavy metals (lead, zinc, nickel, cadmium, copper, chromium and arsenic) by excreting them or storing them in the cell walls of its roots (note 2).

Although the wild form of Thrift has pink flowers, there are cultivated forms with dark pink, red and white flowers. We have a dark pink form in our garden, probably either ‘Splendens‘ or ‘Düsseldorfer Stolz‘ (a.k.a. ‘Dusseldorf Pride’), though it wasn’t named when we bought it. The variety ‘Morning Star‘ is white. Given the choice, I would go for the original unimproved, pale pink wild form.

Armeria maritima makes a very good garden plant. It likes well drained soil and is very drought tolerant, making it a good candidate for growing on a green roof. It is hardy down to -10 or -15 Celsius (UK hardiness rating H5) and can cope with acidic, neutral or alkaline soils.

Thrift grew very happily in full sun on our rockery in North-east Scotland. Here in Norfolk, the three plants we bought about ten years ago have now spread to give a low green mat of foliage in our gravel garden. They need almost no maintenance, just an occasional trim when they start to cover the stepping stone path. Our soil is sandy but the plants are in a north-facing part of the garden and are in deep shade for six months of the year. They don’t seem to mind, although they will flower slightly later than plants in a sunny spot, which is the position the Royal Horticultural society website recommends.

Thrift, Armeria maritima

Mainly in shade, a dark pink Thrift, Armeria maritima, in our garden in Norwich, 28th May 2023.

The common form of Thrift is Armeria maritima subsp. maritima. Its flower stems are usually hairy and reach to 30cm (1 foot) tall. Each flower head is made up of a cluster of flowers, each with five petals, five pinkish stamens and yellowish anthers with cream-coloured pollen.

In the wild there is another form of Thrift, Armeria maritima subsp. elongata, known as Tall Thrift. It has smooth flower stems which can reach 55cm (nearly 22 inches) tall. It also makes a good garden plant but it is a rare plant in in British Isles. In the wild it is restricted to Lincolnshire (note 3).

In the 1950s subsp. elongata grew in at least 12 localities in Lincolnshire, but by 2000 most of these had been destroyed by agricultural “improvement” until just two sites remained, both within the same 1km square. Steps are now being taken to propagate plants and introduce them to nearby sites. One of these sites, Duke’s Covert, is featured on the Rushcliffe Wildlife blog, Wanderings, complete with a photograph of Armeria maritima subsp. elongata.

Outside the British Isles, Armeria maritima is native and has a widespread distribution in the Northern Hemisphere. Armeria maritima subsp. elongata has a more restricted range, occuring in Europe as far east as Ukraine, Belarus and part of Russia, from Iceland and Norway in the north down to Italy in the south.

The Plants For A Future website tells us that Thrift leaves are edible when cooked and that the dried flowering plant has antibiotic properties and has been used in the treatment of obesity, some nervous disorders and urinary infections. However, the plant is known to cause dermatitis or local irritation, so can’t be used externally as an antibiotic poultice. I haven’t tried eating it.

Richard Mabey speculates about the origin of the name “Thrift”. One theory is that it it is derived from “thriving” – the plant grows well in many places. But perhaps it refers to the way the leaves curl up to conserve water. “Thrift” also refers to economical management, economy and frugality and for this reason the plant was featured on the old thruppenny bit (British 3d coin) from 1937 to 1952. I used to have several of these coins but they stayed behind when I left home and I haven’t seen any for many years. John Grace kept his and there is a photograph of one on his Botany In Scotland blog.

Thrift with Small Copper butterfly

Thrift with Small Copper butterfly. Island of Seil, late May 2018.

If you’d like to read more about Thrift I recommend the Botany In Scotland blog. There are some excellent photographs, including close up pictures of flowers, on the Wildflower Finder website.

Notes

Note 1 – From from pages 112 – 113 of Richard Mabey’s “Flora Britannica” (Sinclair-Stevenson, 1996).

Note 2 – Thrift is a halophyte – a plant that is tolerant of salt. I wrote about another halophyte, Danish Scurvygrass, in May 2016. Danish Scurvygrass has been able to spread along our road network because of its tolerance of their salty edges. Thrift has been able to do this too, but to a lesser extent.

The Wild Flower Finder website explores heavy metal tolerance in plants.

Note 3 – The BSBI map shows a distribution spot in southern England too, described in the the Rushcliffe Wildlife blog, Wanderings, as “near Aldershot”. Presumably it’s an introduction but I haven’t been able to find out any more details of this site – please contact me if you know more.

Posted in Ornamental | Tagged Armeria maritima, Thrift

Japanese Kerria, Kerria japonica

Jeremy Bartlett's LET IT GROW blog Posted on 29 March, 2024 by Jeremy Bartlett29 March, 2024

Last week’s beautiful and unexpected plant treat was a single-flowered Kerria japonica (Japanese Kerria) in a front garden on Earlham Road in Norwich.

Too many gardens have become barren car parks and it is always a pleasure to see one full of plants and even better when it’s full of unusual and interesting plants. Floating above a carpet of tiny Lesser Celandine flowers, the Kerria japonica was stunning, a cheery yellow on a mostly grey spring day.

Kerria japonica

Kerria japonica (Japanese Kerria). The single-flowered form. 21st March 2024.

Kerria japonica (single flowered)

Like the plant I saw on Earlham Road, the wild form of of Kerria japonica has open, single yellow flowers with five petals (note 1). The flowers remind me of the beautiful yellow rose Rosa xanthina ‘Canary Bird’ which we grow in our back garden. This is not surprising, as roses and Kerria are both members of the Rose family, Rosaceae.

But I’ve only seen single-flowered form twice. I usually see the double-flowered form in gardens, Kerria japonica ‘Pleniflora’.

Kerria japonica ‘Pleniflora’

I think Kerria japonica ‘Pleniflora’ lacks the charm of the single-flowered form but it’s still a cheery plant and it was always easier to find in garden centres. I first grew it as a ten year old child in my garden in Scotland and it brings back happy memories.

Kerria japonica spreads by suckering shoots to form a thicket of stems and one of these shoots spread from a neighbouring allotment through a Lawson’s Cypress hedge into the edge of my plot, where it was a welcome visitor.

Kerria japonica 'Pleniflora'

Kerria japonica ‘Pleniflora’ in our back garden. Early April 2017.

I dug up some of the suckers and introduced them into our garden at home. We were planting up Grapes Hill Community Garden in Norwich at the time (spring 2011) and I used another sucker to introduce Kerria japonica ‘Pleniflora’ there too.

An Adaptable Plant

In the wild, Kerria japonica grows in in thickets on mountain slopes in China, Japan and Korea. It is the only species of Kerria.

Both forms of Kerria japonica are cheerful, adaptable and long flowering shrubs. The main flowering period is spring, from March until early May, but there can be a smaller flush of flowers in August.  Kerria japonica has alternate, simple “birch-like” leaves with a doubly serrated margin.

Kerria japonica grows happily in many different aspects, from full shade to full sun. I think it looks at its best in dappled shade; flowers soon bleach in full sun. It tolerates most soil types but dense soils can sometimes cause the roots to rot. I have grown it in loam and in rather sandy soil.

With its suckering habit Kerria japonica soon develops into a thicket of tall, graceful stems, which can cover up a wall or fence, even in dark corners or against north-facing walls.

Stems grow to six to ten feet (1.8 – three metres) tall and the plant can spread to a similar width. Any spare suckers are easy to chop off with a spade and can be used to make new plants and, perhaps, new gardening friends. But this is the way the plant renews itself, so leave some to grow. Old, dead stems can be cut back to allow air into the centre of the shrub and to keep it tidy. The time to prune is after flowering, in June and July. It’s best to take cuttings from August to October, though I’ve dug up roots in early spring and, with enough watering, they’ve taken well. (But please read below about Kerria Twig and Leaf Blight below before you give away cuttings.)

Kerria and Wildlife

The Gardeners’ World website says Kerria ‘Pleniflora’ has no particular known value to wildlife in the UK. Double-flowered plants tend to lack pollen and nectar, so are usually pretty hopeless for insects. However, on one sunny day in early April 2017 we saw two species of hoverfly and a Conopid fly visiting the flowers in our back garden (note 2). The hoverflies may have been attracted by the yellow flowers rather than any reward; the Conopid fly would have been hanging around waiting for a solitary bee to parasitise.

I haven’t seen the single-flowered forms of Kerria japonica often enough to see any insects on the flowers. The Wildflower Web website says that “the plant is also a favorite of pollinators, including bees and butterflies, making it a great choice for those looking to attract wildlife to their garden”. Please let me know if you have any observations.

Kerria japonica 'Pleniflora'

Seeing double: Kerria japonica ‘Pleniflora’ with Syrphus sp. hoverfly. 2nd April 2017.

Kerria japonica and Myopa sp.

Kerria japonica and Conopid fly (Myopa sp.). 2nd April 2017.

Other Names

Kerria is named after the Scottish plant collector William Kerr (note 3). The specific name “japonica” refers to Japan.

As well as Japanese Kerria, Kerria japonica is known as Jew’s Mallow and Kerria japonica ‘Pleniflora’ is sometimes known as Bachelor’s Buttons. The Wildflower Web website also gives the names Easter Rose, Japanese Marigold Bush, Japanese Rose, Miracle Marigold Bush, Yamabuki and Yellow Rose (note 4).

Kerria Twig and Leaf Blight

All is not well with Kerria japonica.

In 2018 we noticed that our Kerria japonica was dying back. At first I thought this was because of the long summer drought but more recently I realised the plant had Kerria Twig and Leaf Blight, caused by the ascomycete fungus Blumeriella kerriae. 

The RHS website gives the symptoms:

  • On the leaves the infection starts as small red-brown spots (1 – 5 mm diameter) with dark purple borders and yellow haloes. Spots are visible on both leaf surfaces and sometimes number in the hundreds on a single leaf
  • In wet conditions the spores of the fungus may be visible as white clusters in the centre of the spots
  • As the infection progresses the spots coalesce and the leaves turn yellow through to brown and fall from the stems
  • Stem lesions appear as purple-brown, slightly-sunken elliptical cankers which remain visible on the stems throughout the year. Cankers which girdle the stem result in extensive stem die-back.

The Fungi of Great Britain and Ireland website has descriptions and photographs of leaf lesions and microscopic details, including conidia (the asexual spores; the sexual, teleomorph stage of the fungus is not known in the British Isles).

Stem lesions on Kerria japonica caused by Blumeria kerriae

Stem lesions on Kerria japonica caused by Blumeria kerriae.

Since the first infection I’ve cut off and binned the diseased shoots but the fungus has taken hold and the few shoots that our shrub produces no longer grow as tall or as strong as they did in 2017. I know of other people who have dug out their Kerria plants.

Blumeria kerriae spores are thought to be transferred between plants via rain splash, wind, and transfer on contaminated tools.

Blumeria kerriae overwinters on fallen leaves and lesions on the stems then releases spores to reinfect new growth in spring. Spore production has been observed throughout the year on Kerria plants in the UK.

Blumeria kerriae was known in the United States but the first observations in the British Isles date from 2014. Presumably it came here on diseased plant material.

If you grow Kerria japonica and intend to pass on cuttings from your plant, please make sure it has no signs of disease.

Sadly, the occurence of Blumeria kerriae in the British Isles means that Kerria japonica is no longer the tough, disease-free plant it once was.

Happily, the Earlham Road plant looked healthy. I’ll enjoy it while I can.

Kerria japonica

Kerria japonica (Japanese Kerria). The single-flowered form. 21st March 2024.

Photographs by Vanna Bartlett, except for stem with Blumeria kerriae.

Notes

Note 1 – ‘Simplex’ and ‘Golden Guinea’ are named, single-flowered forms of Kerria japonica.  The latter has been given an Award of Garden Merit (AGM) by the Royal Horticultural Society, as has the double-flowered ‘Pleniflora’. There is a variegated form too, if you like that sort of thing.

Note 2 – The hoverflies were a male Eupeodes luniger and a species of Syrphus.

Note 3 – William Kerr was born in Hawick in the Scottish borders. He sent back to Britain examples of 238 plants new to European gardeners and to science. He died in 1814.

Other plants William Kerr brought back include Euonymus japonicus, Pieris japonica, Nandina domestica and Rosa banksiae.

Note 4 – Yamabuki is the Japanese name for the plant. According to the Yamabuki Japan website, he word was first used in the description of spring scenery in the oldest Japanese poem, “Manyo-shu”.

Posted in Fungi, Ornamental | Tagged Bachelor's Buttons, Blumeria kerriae, Japanese Kerria, Jew's Mallow, Kerria japonica, Kerria japonica 'Pleniflora'

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