Echiums of Macronesia
Question: What grows 15 feet in 2 months
and likes Canaries? Flushed with success from his recent TV appearance,
Richard provides the answer.
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Richard Darlow, 106 Vaughn Road, Gawber, Barnsley
Chamaerops No. 16, published online 23-08-2002
Echium wildprettii on Mt. Teide, Tenerife.
Anyone who has spent a holiday in Tenerife or Madeira,
or visited Tresco and the Cornish coast - particularly in late spring
or early summer - cannot have failed to notice wonderful tall spires
of blue or red flowers. Having seen them, their identity may not
always be realised as relatively few horticultural books describe
them or give any clue as to their cultural requirements. For several
years, I did not know what they were but I'm now pleased to be better
acquainted with them; they are species of Echium and belong to the
Boragitiaceae - the Borage family.
There are around 40 species of Echium consisting
of annuals, biennials and shrub-like perennials. Their distribution
is mainly throughout Europe, western Asia, Africa and Macronesia.
Flower colour is predominantly blue, but red, pink, mauve and white
species are to be found too. Many European species are small growing
annuals, which are not particularly showy; the blue flowered British
native 'Vipers Bugloss' - E. vulgare - is an example. It is however,
those species which are native to Macronesia - that is Madeira,
the Canary islands and the Azores - that are most frequently cultivated
and which produce the most spectacular of flowers.
There are two distinct types of Macronesian Echium:
biennials (or triennials) and shrubs.
The former are monocarpic and produce a rosette
of leaves in their first year, which elongates and develops into
a flower spike during the second year, but sometimes this is delayed
until the third. This mirrors the growth characteristics of common
garden plants such as Digitalis and Verbascum. After flowering,
large quantities of seed are produced then the plants die. Shrub
species of Echium are semi-woody perennials forming large rounded
bushes. Each branch radiates from a woody stem; leaves are usually
confined to the non-woody tips and are arranged in rosettes. Flower
spikes are produced each year from the leaf rosettes - new rosettes
developing from the bases of the dead flower spikes.
The largest and possibly the best known and most
spectacular species is E. pininana, a biennial from the Canary Isle
of La Palma - one of the wettest of these islands - where it grows
at altitudes of up to 500m. This species is commonly grown in many
coastal Cornish gardens and at Tresco, self-seeding freely (almost
like a weed but what a weed!) and is unharmed by most winters on
the mainland. Huge rosettes - up to 4 feet across - of green, rough-textured
leaves are produced in the first year from seed. Leaves are 2 feet
or more in length and S or 6 inches broad, tapering to a point.
The undersides are covered in many fine hairy 'spines', which can
lodge in your fingers if handled! A stout trunk-like stem develops
as the leaves become more widely spaced; the rosette reaching 3
or 4 feet in height by the end of the first year. The stem is also
covered in fine white spines but becomes increasingly woody at the
base where it can be 3" thick.
During late winter of the second (or third) year,
the stein rapidly elongates and the leaves become progressively
shorter and narrower; tiny flower buds are formed between the upper
leaves and for some way above the leaves. In the space of around
2 months, the plant thrusts upwards to a height of 12-15 feet or
even higher, forming a tapering spire of thousands (millions?) of
tiny blue flowers. The bell-like flowers have protruding stamens,
each one fading to a mauve-pink colour as further flowers continue
to open over a long period. The flowers are a haven for bees and
invariably become a 'hive' of activity! A single flowering plant
is a magnificent sight; a large group is breathtaking.
E. fastuosum is a shrub species forming a mounded
dome, S or 6 feet high and the same across. Leaves are 6-8 inches
in length and are green with silvery hairs. Masses of flower spikes
are produced; each one like a miniversion of E. pininana, 2 or 3
feet in length. They are a darker shade of blue. E. fastuosurriis
known as 'Pride of Madeia' and believe it or not, this is where
the plant originates! A hybrid between E. pininana and E. fastuosum
produces the large blue flower spikes of one parent and the shrubby,
branching perennial habit of the other.
Several similar species also originate from Madeira.
These include E. candicans, which has blue flowers although it is
sometimes regarded as a synonym of E. fastuosum, and E. nervosum.
The latter has silver-grey leaves, which are covered in soft silky
hairs, while the flowers are pale mauve with red stamens and are
borne in small spikes.
From the Canary Isles, shrub types in cultivation
include E. webbli, found in woodland at altitudes of 500-1800m on
Las Palmas. This densely branched plant has quite broad silvery
leaves and small spikes of blue flowers. E. callithyrsum from Gina
Caanna has lanceolate or ovate hairy leaves and short, deep blue
inflorescences. They grow on cliffs at heights of 800-1500m.
Perhaps the showiest species (and my personal favourite)
is E. wildprettii, a biennial, native to Tenerife and La Palma.
Growing at altitudes of 1600 - 2000 metres, this 'alpine' can be
seen above the winter snow line in the crater of Las Canadas and
on the slopes of Mount Teide in Tenerife. The climate here is warm
and moist in summer but dry and cold in winter.
Superficially resembling the Hawaiian 'Silverswords'
(Argyroxiphium sp.), this plant starts off by producing a rather
flat rosette of soft, narrow, silvery leaves, some two to three
feet in diameter. The rosette does not elongate until the second
or third year when the flower spike rockets upwards to some 10-12
feet. The spike is broader and squatter than that of E. pininana
and the flowers are more densely packed, commencing closer to the
ground. The most significant feature of E. wildprettii is that it
has red or dark pink flowers with red stamens.
All of he species I have described can he seen at
Tresco Abbey Garden along with several others. Echiums hybridise
freely and many of he plants at Tresco are hybrids, providing a
range of flower colours from the palest mauve to the darkest purple
and almost every shade of blue in between, All of the Tresco hybrids
are referred to as E. x scilfoniensis. Echium pininana has hybridised
with E. wildprettii to produce huge pink and mauve flowered forms.
If you visit the gardens at 'Fresco in late May, you will find flowering
Macronesian Echiums are not very hardy, but this
is only to be expected considering their origins. In addition to
the Scilly Isles and Cornwall, they grow well (and become naturalised)
in the Channel Islands, the Isle of Wight, and in mild, moist coastal
gardens of Devon, Somerset, Wales and Western Scotland. Other favoured
parts of Europe include the Mediterranean coast, and along the coasts
of Brittany and the Cherbourg peninsular in Northern France. They
also grow very well in the warmth of central London. Echiums cams
tolerate some frost however and will be little damaged by frosts
of -2° or -3°C. Below these temperatures plants will possibly
experience defoliation, and are likely to be killed at anything
below around -5°C. Even in Cornwall, during the severe weather
of February 1991, virtually every Echium plant was killed. Fortunately,
many re-appeared due to the large quantities of seed that germinated
in the warmer weather and by 1992, there were masses of flowering
plants once again.
On 5-9-2000 Phil
I also find these plants as fascinating as
Palms for their architectural and exotic form. I have often gathered
seed from Cornwall of E. Pininana and also E. Wildprettei from Tenerife.
They grow from seed easily which is also readily available from
several seed sources in UK - Secret seeds in Devon supply many types.
I have only managed to get Pininana through one winter here in Surrey(1999)
and I had a small flowering,but alas no towering spike! However,
the seeds that fell from that time have continued right up to this
year(2002) to throw up new seedlings each year - about 6 plants
annually although I have probably inadvertendly weeded out others.
Obviously a full spike could provide a multitude of plants for some
years. One technique that I have discovered in an attempt to keep
the stock going is to raise them from cuttings. Often a small side
branching will form and I have removed these and immersed the base
in water. Roots will soon form and then I have added a compost to
the water gradually thickening it up to prevent damage to the sensitive
roots. These cuttings will then be of manageable size to overwinter
in a greenhouse ready for planting out in the spring. Timing this
right may enable the plant to flower in its second year rather than
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