Yew Trees
Above: My drawing of the yew tree (Taxus baccata) which I modified to make my dryad picture! This
drawing was based upon a photograph of a yew tree in Kingley Vale National nature Reserve in England
(as shown in Gareth Lovett Jones and Richard Mabey's superb book - The Wildwood, In search of
Britain's Ancient Forests, Aurum press, ISBN 1 85410 242 7 - this is one of my favourite books and the
photography is fantastic and all the work of Gareth Jones). Kingley Vale is probably the finest Yew wood
in Europe.

Description

As the authours of The Wildwood themselves rightly say, these trees almost look like animals with their
muscles and sinews tensed and ready to move, as if frozen in time. Indeed the tree above not only
reminds me of an elephant, and looks as if a mouth could open up at any time, as if the tree is poised
and trying to speak!

Yew trees are short trees (10 to 20 metres tall), but they can reach enormous girths with trunk diameters
of 4 metres, but they are slow growing and so may take 2000-4000 years to reach such dimensions.
They are Britain's longest lived trees and one of only three British species of conifer (the other too being
the juniper and the Scot's Pine). The oldest specimen in Scotland has its age disputed, most put it at
2000 years of age, though some put it at around 9000 - it is very hard to tell since this specimen is
hollow. This most ancient British yew tree is the Fortingall Yew in Perthshire Scotland, whose age could
be anywhere between 2000-9000 years, though most hedge their bets with the lower of these estimates.
However, other specimens in Britain are estimated at over 5000 years, and though sceptics claim that
such estimates are 'fanciful' they are nevertheless quite possible. The controversy continues. The
Fortingall Yew measures over 17 metres in girth (circumference of trunk) and has split into several living
fragments, earning it the description of a 'wood-henge'.

The yew tree is certainly a tree of endurance, and even when dead its wood is the slowest to decay, and
outlives iron, with the oldest wooden artefact discovered being a yew spear, over 250 000 years old,
and was discovered in England. Yew wood was prized for its use in bows, particularly with its very
different sap wood and heartwood (which differ greatly in colour and in elastic properties) making it ideal
for composite longbows.

Reproduction and Life Cycle

With all these connections of rebirth, the yew tree is often thought of as feminine in character - as the
birch is also feminine and the oak is masculine. However, to me it has a certain androgynous character,
and coincidentally the yew tree is also sometimes confused about its gender - individual yew trees are
usually male or female (dioecious) but some individuals bear both male and female flowers (they are
monoecious) and some have the odd branch that is a different sex to the rest of the tree and others may
change their gender over time! Yew trees have a remarkable ability to come back to life from senescent
states. Often the sweeping branches root in the soil around the tree and eventually become a grove of
new trees, a process that can repeat seemingly indefinitely. Also a branch may root inside the hollow
trunk of an old yew and again grow into a new tree taking the place of the old.

Yew trees take about 70 years to mature (ranging from 30 to 120 years) and are shade and sun
tolerant. They are slow growing and reach 20-28 metres in height and often form multiple stems and
asymmetric crowns. The trunks are fluted in older trees and branches bare alternate green twigs. As far
as conifers and gymnosperms go, the yew is unusually resistant to pruning, even back to the main trunk,
due to epicormic buds. A study of English churchyard yews (see
Inspiration to humankind below)
showed that tree age could be estimated as the girth in cm squared divided by 310.

Asexual reproduction occurs when the sweeping branches touch the ground and self-root (natural
layering). New shoots can sprout from a stump.

Yew trees are difficult to age. Older trees are frequently hollow and often rings are very hard to see or
missing or incomplete (such that many more rings may be counted on one side of the trunk than the
other). In cross-section it can be seen that many yew-tree stems have multiple cores, frequently two but
as many as 7 being reported. This could arise from multiple stems fusing together, parent stems fusing
with nearby seedlings, the inclusion of branches by the expanding trunk or the presence of woody
adventitious roots in the centre of old (and otherwise hollow) trunks. Yew trees seem to easily fuse with
and incorporate other structures into their wood, such as rocks.

Cones

As a conifer, the yew does not have true flowers for its male 'flowers' will actually become strobili or
cones. These small male cones are 2-3 mm in diameter and each consists of about 6 to 14 stalked
microsporophylls (small modified leaves for pollen production) each with 4 to 9 pollen sacs. Clusters of
20-30 of these cones occur near the branch ends. Female 'flowers' are .5 to 2.0 mm long and occur
singly or in pairs in leaf axils on the underside of shoots. Each consists of several scale leaves, the
uppermost being fertile and bearing a single ovule.

Flower buds form in late summer, open in late winter and the cones open about 100 days after the
temperature drops below 10 oC in autumn. The plant is wind pollinated. The nucellus secretes a sugary
fluid that accumulates at the micropyle as a drop that traps the wind-borne pollen and then the drop is
reabsorbed, drawing the pollen to the nucellus where it germinates. The male gametes are
non-motile.(This process is similar in
pines). Unlike that of pine trees, the pollen of yews have no air
sacs.

Being a conifer the yew tree does not produce fruit that enclose the seeds completely, rather it has
'naked seeds' though the female cones are highly modified - each partially encloses but a single seed
some 4-7 millimetres long, in a bright red fleshy cup 8-15 millimetres in diameter and open at one end,
called an
aril. This fleshy aril attracts birds who eat the arils and disperse the seeds in their droppings.
Seeds are shed in late summer and early autumn. Breaking apart an aril will reveal a slimy secretion,
earning them the colloquial name of 'snotty-gogs'! The aril is the only part of the tree that is not highly
toxic, and some say it is harmless - though I don't recommend eating them, the mucilage does taste
sweet! The male cones are globular. The seeds take about one year to develop and average about 57
to 70 mg in mass. The seeds are dispersed by birds that feed upon the fleshy arils. The germling has
two cotyledons and germination is of the epigeal type.
References / Bibliography

  1. G.L. Jones and R. Mabey, 1993. The Wildwood: In search of Britain's ancient forests.
  2. P.A. Thomas and A. polwart, 2003. Taxus baccata L. Journal of Ecology 91: 489-524.
"But when Merlin saw such great crowds of men present he was not able to endure
them; he went mad again, and, filled anew with fury, he wanted to go to the woods, and
he tried to get away by stealth. Then Rhydderch ordered him to be restrained and a
guard posted over him, and his madness to be softened with the cither; and he stood
about him grieving, and with imploring words begged the man to be sensible and to stay
with him, and not to long for the grove or to live like a wild beast, or to want to abide
under the trees when he might hold a royal sceptre and rule over a warlike people. After
that he promised him that he would give him many gifts, and he ordered people to bring
him clothing and birds, dogs and swift horses, gold and shining gems, and cups that
Wayland had engraved in the city of Segontium. Every one of these things Rhydderch
offered to the prophet and urged him to stay with him and leave the woods.

The prophet rejected these gifts, saying, 'Let the dukes who are troubled by their own
poverty have these, they who are not satisfied with a moderate amount but desire a
great deal. To these gifts I prefer the groves and broad oaks of Calidon, and the lofty
mountains with green pastures at their feet. Those are the things that please me, not
these of yours - take these away with you, King Rhydderch. My Calidonian forest rich in
nuts, the forest that I prefer to everything else, shall have me." (Geoffrey of Monmouth,
1150. Vita Merlini.)

For it was in the depths of the wildwoods that Merlin's power was born.
Yew tree

Leaves

The leaves are lanceolate (blade-like), flat, dark green, 1-4 centimetres long and 2-3 millimetres broad,
arranged in spirals on the stem, but as the shoot grows, the leaf bases twist to align the leaves into two
flat rows, one on either side of the twig. The optimum temperature for photosynthesis is 14 to 25 oC (but
will occur from -8 to 41 oC). The rate of photosynthesis declines in old needles, reducing to 50% in
7-year old needles. Tolerance to air pollution, including sulphur dioxide is high. All parts except the
fleshy arils are poisonous and contain the alkaloid taxin (or taxine) which prevents cardiac cells from
functioning. Other alkaloids include taxanes and taxol, which are anti-cancer or anti-tumour agents and
taxoids and taxotene.
Stomata occur on the undersurface of the needles only within two stripes, though
not in rows. They show xeromorphic features, being sunken with raised subsidiary cells. About 28
needles are produced per shoot per year and each needle lives for 4-8 years.

Bark

The bark is thin and scaly and brown to greyish-brown or reddish-brown, with fine vertical furrows,
gnarled in places, giving the tree a smoothish sinewy appearance. Four year old saplings still retain
photosynthetic cork cells in their bark and an intact epidermis in parts (formed during primary growth of
the stem). The periderm (outermost layer of bark) is single and consists of 10-15 layers of phellem
(cork) cells arranged in layers with alternating thin and thick-walled cells. There are no lenticels.
The phloem (inner bark that conducts sugary sap) contains sieve cells 150 to 200 micrometres long.

Wood

Yew wood lacks axial parenchyma (strands of parenchyma cells parallel to the long axis of the trunk or
branch) and lacks resin canals, except when traumatised, then resin canals (see
pine) form. The
sapwood is pale, the heartwood reddish. The annual growth rings show gradual transitions. The wood
has a density of 640 to 800 kg/m^3 and is hard, heavy and flexible. It was used extensively in the past in
composite longbows. The tracheids are narrow and have pits arranged in single rows and spiral
thickenings in their walls. Alcoholic extracts of the heartwood are antifungal and reduce the growth of
Gram Negative bacteria, but not Gram Positive bacteria.

Roots

The horizontal roots are extensive (as in beech) and can penetrate deep into rock fissures as in
limestone pavements (indeed they are famous for this ability).
Mycorrhizas are of the endomycorrhiza
type only. The roots form a thick mat of ramifying fine roots near the soil surface. Once the girth of the
trunk exceeds 4.5 metres it is likely to be hollow and adventitious roots grow down from the living outer
wood into the hollow cavity to reabsorb nutrients from the decaying heart wood.

Habitat and habit

Yew trees prefer well-drained chalk and limestone soils, and this accounts for the location of Kingley
Vale in the South Downs area (which consists of gentle rolling chalk hills). Yew prefers neutral to alkaline
soils and may form pure woods on chalk (as on the South Downs) and may be the dominant tree on
steep chalky slopes but more often grows as a member of mixed woodland. The yew prefers humid
oceanic climates with mists, high rainfall and mild winters (e.g. the lowlands of the Lake District). High
winds stunt growth. It has the densest and darkest foliage of any evergreen. When young, the yew tree
has the typical conifer cone-shape resulting from monopodial growth, but in older age resembles more a
very short and wide oak tree in form - (I read somewhere that this is due to a transition to sympodial
growth, though I have been unable to verify this). Some types appear to retain the youthful cone-shape,
especially those in Ireland it is alleged.

Inspiration to humankind

The yew has played a tremendous (though not well known) role in shaping religious beliefs, being
associated with immortality and rebirth or spiritual resurrection. To the ancient Celts and Druids it was a
sacred tree and adorned many of their religious sites. Christian churches in Britain were often built on
these ancient religious sites, and inherited the yew trees already there - one can find a yew tree in many
a churchyard. (Another factor in this might be that the all parts of the yew tree are poisonous and so it
was removed from land where sheep were set to graze and presumably sheep were kept from
churchyards). The centre of Christianity in ancient Britain was apparently the island of Iona, literally
'Island of the Yews' and it was possibly the former centre of a druidic yew cult. These moves have often
been interpreted as an aggressive act to forcibly convert the druids by taking over their sacred sites,
and this may well have been, though the churches adorning these sites incorporated much druidic
symbolism in their architecture, which suggests a more gradual transition (it should be remembered that
religions constantly change over time and the form of Christianity introduced may not have differed so
very much from Druidism and so may have been voluntarily accepted by many - indeed some ancient
Christian literature is far more in tune with mystical philosophies than modern orthodox interpretations
and many scholars throughout antiquity drew parallels between such apparently diverse beliefs). Some
Druids were to have their Mythos rewritten to transform him into a Christian saint. In some early forms of
Christianity, Jesus was the Light of Nature (as in the ancient Gospel of Thomas), the Spirit that pervades
all things, and thus identical to the Spirit of the Trees and the Nature Spirit. Such an idea was already
well founded in Druidism and the Druids may have easily accepted this form of Christianity. To the
Druids, this Spirit had many symbols, including Jack Green, who perhaps not surprisingly adorns many
cathedrals! To many, characters like Christ and Merlin were poetic expressions of the same inner truth
and hidden Light. This 'hidden' light or Holy Spirit was the inspiration behind much of Occultism (though
not the 'occultism' understood by many) with 'Occult' meaning 'hidden'. When alchemists spoke of the
'Occult', often represented by mysterious symbols and mythical beings like the Unicorn, they referred to
the spiritual truth as revealed by the poetic, philosophic and mystic Spirit of Truth also known
philosophically as the Holy Spirit, which as the Gospel writers and the Buddhists and Taoists before
them made clear would only be understood by a minority and hence was 'hidden', by the will of God they
sometimes believed, from the masses. Thus, there has always been an esoteric side to mainstream
religion which was largely in tune with mystic traditions across the World. As a final connection, it is worth
noting that yew branchlets served as palm substitutes on Palm Sunday.

To the Neo-pagans and new Age movements, the yew tree continues to be important as a symbol of
rebirth and immortality (similar ancient ideas may well have connected it to the Passion). It has been
suggested that the yew symbolised the Tree of Life - an ancient mystical concept which appears as early
as 5000 BC and runs through Egyptian Mysticism, Jewish Mysticism and Christianity, right up to today.
Thus, trees have influenced religion and mysticism more than most dare to imagine! This is not
surprising, considering their majestic beauty and their ability to resonate with our inner selves. Trees
have always been associated with wisdom and spiritual sacrifice. The word 'Druid' is linked to the word
'Duir' another name for the oak, and the Druids were said to be the 'Children of the Oak' meaning that
they were reborn into spiritual wisdom. The word 'wizard' probably had nothing to do with evil sorcery,
but was rather someone 'wizened' in the knowledge of hidden light (hidden as the Holy Spirit or Spirit of
Truth is hidden to those who 'have eyes but cannot see'!). The Norse god Odin hung himself from an
Ash tree (the Tree of Life, Yggdrasil) to acquire the wisdom of the Runes. Osiris was encased in a
wooden column prior to his resurrection, and Christ was said to have been crucified upon the remains of
the Tree of Life (of which he was said to be a part) in order to restore it to fuller life. The yew tree has its
own character (of course) and its short stature and sweeping branches cause it to form a natural vaulted
'cathedral' beneath which little else grows, whilst the hollow trunk of an ancient yew may have been
symbolic of an 'inner sanctum'. To the Neo-Druids it symbolises the womb of Mother Earth, and passing
in and out is symbolic of spiritual rebirth. In alchemy, trees symbolised the spiritual connection between
Heaven (the Kingdom within!) and the physical Earth as well as harmony, since their life depended on a
unity of the four elements: fire from the Sun, water and minerals (earth) and of course the air. The
harmonious union of these four elements was said to give rise to spirit (i.e. life) and also to inner
harmony. Again this links to the Resurrection. The study of such topics is like trying to solve an ancient
mystery and can be fruitful, from an artistic and philosophic point of view, but I suspect that much of the
truth of these mystery traditions is lost forever in the mists of time. One fact is certain, however, trees,
including the yew, were, like the Sun and Moon, instrumental in the formation of just about all literary and
religious traditions and a major inspiration to many artists. It seems that the 'wise' were always
associated with trees:
Male cones of yew
Above: male cones of the yew. The cone is borne on a short stalk surrounded at their bases
by papery brown-yellow bracts. The two cones on the left have opened up their scales to
release their pollen.