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TREE MALLOW

Malva arborea

Mallow Family [Malvaceae]

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category
category8Trees
category
category8Broadleaf
status
statusZnative
flower
flower8mauve flower8purple
inner
inner8indigo flower8black
morph
morph8actino
petals
petalsZ5
stem
stem8round
rarity
rarityZuncommon

9th June 2016, coast, Deganwy, North wales. Photo: © RWD
Grows up to 3m tall especially near the sea and usually either in the high-tide zone or just above it. Rarely found inland, but when it is it could be confused with the escaped Garden Mallow (Malva × clementii) aggregate of species.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
Preferring the salty environment nearer the coast to deter many potential competitors from growing (but not all) Tree Mallow has to have some defence against excess salt in its diet. It does this by excreting salt through glands on its leaves. Even its seed cases are protected from salty sea water by an impermeable outer case which allows it to remain viable for many years, perhaps long enough to reach the shores of other lands especially those around the UK coasts, but it does prefer the warmth and dislikes the cold. It is a shrubby biennial or perennial. This specimen looks sturdy as if it might have been growing for longer than two years compared to specimens just slightly more inland (shown below) which have far thinner trunks.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
The tree is very shrubby with many branches, all seemingly flowering.


7th March 2017, grassy coastal dunes, Lytham, Fylde Coast. Photo: © RWD
Another specimen, this one lacking the strongly-upwardly curved branches.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
A less-sturdy specimen a little further from the salty sea-water but the ground will still certainly be subject to salty sea-spray. Perhaps that is why these specimens have a much thinner bole with no need to store much fresher rain-water? Or, with it being a biennial, they could just be only up to 2 years old. Don't they grow fast!


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
Conwy mountain is in the distance over the estuary and the railway line to Llandudno protects it from most of the ravages from the sea.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
The flowers are in sparse racemes up the stems. Leaves palmate with between 5 to 7-lobes.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
The flowers have little or no gaps between the darker-coloured pinkish-purple petals with a dark indigo centre which are 14-20mm long, un-like the much rarer Smaller Tree Mallow (Malva pseudolavatera) which has wider gaps and slightly shorter petals 10-20mm long which are a paler lilac colour and lack the darker centre.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
Leaves shallowly lobed with 5 to 7 lobes, the two rear ones shorter.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
The flowers flare out from within the hairy calyx and epicalyx. The young stems are hairy too.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
The flowers are initially spirally wrapped into a cone which unwraps.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
All the younger parts are hairy. A developing fruit is just above centre.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
Petals usually recurved backwards slightly. Unlike Smaller Tree-mallow the central area is indigo coloured with darker stripes on the petals.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
Mallow are rather different regarding sexual organs, there is a central tube up the centre of which is the style (not visible in this photo). Around the tip of the tube numerous stamens grow bearing pale lilac-coloured pollen.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
The central style is visible in this specimen as well as the pollen-bearing stamens.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
The stigma has a white style split into several curved sections.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
Epicalyx has 3 lobes and is larger than the calyx just visible behind the flower.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
An un-opened flower showing the 3 larger open flaps of the epicalyx and the 5 closed flaps of the calyx. All hairy.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD


9th June 2016, coast, Deganwy, North wales. Photo: © RWD


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
Both Smaller Tree-mallow and Tree Mallow have some stellate (star shaped) hairs on the young parts of the plant.


9th June 2016, coast, Deganwy, North wales. Photo: © RWD
The trunk of this specimen is quite striking with its symmetrical U-shape and a bole which thickens rapidly nearer the ground. The hemi-circular paler ridges are also distinctive. The lower parts of the bole(s) are woody and reddish-brown, but the upper parts are still green. It is obviously suffering - the lower leaves are drooping like handkerchiefs, some turning brown, and many have fallen on the surrounding beach pebbles and boulders below. In the foreground is Sea Barley. Living on the sea-front subjected to twice-daily tides your Author speculates that this specimen may have to eliminate salt at a much greater rate than the specimens further inland, and that this might account for its more succulent appearance?


7th March 2017, grassy coastal dunes, Lytham, Fylde Coast. Photo: © RWD
This specimen also exhibiting the strongly upwardly-curved branches.


7th March 2017, grassy coastal dunes, Lytham, Fylde Coast. Photo: © RWD


GARDEN TREE-MALLOW

(showing details of the similar arrangements of style and anthers and stellate hairs)
28th June 2009, a garden, Walkden, Gtr M/cr. Photo: © RWD
This flower (that of Gargen Tree-Mallow and NOT Tree Mallow itself) admirably demonstrates the strange arrangement of male and female parts: the reddish style emerges from the tip of a long translucent tube or sheath and splays out into numerous stigmas. Meanwhile the numerous filaments are pink and peel away from the central tube at intervals, each with a cream-coloured anther at the tip. (The exact shape and colour will obviously slightly differ for the stamen/stigma assembly of Tree Mallow)


28th June 2009, a garden, Walkden, Gtr M/cr. Photo: © RWD
Similarly this young hairy stem from Gargen Tree-Mallow, like those of Tree Mallow and Lesser Tree-Mallow but probably slightly different in ways unknown, have some hairs that are stellate: star like - they branch (at the base) into several, like a star.


Easily mistaken for : Garden Tree-Mallow (Malva × clementii) (formerly Malva thuringiaca) aggregate of species, a perennial horticultural shrub which has larger and paler flowers and only one at each leaf node but which grows inland only and is not salt-tolerant. Your Authors only lasted 3 or 4 seasons before dying.

Some similarities to : Lesser Tree-mallow (Malva pseudolavatera) but that has paler petals that are lilac and which lacks darker stripes and indigo-coloured blotch in the centre which also inhabits rough ground near the sea. It is a lot rarer occurring in the Scilly and Channel Islands.

It is a short native Tree which is tolerant to sea-water salt preferring to grow near the sea or on the beach near normal high tidal. It grows on waste ground, rocks, and the bottoms of cliffs. It seems not to grow at all far from the sea.


  Malva arborea  ⇐ Global Aspect ⇒ Malvaceae  

Distribution
 family8Mallow family8Malvaceae

 BSBI maps
genus8Malva
Malva
(Mallows)

TREE MALLOW

Malva arborea

Mallow Family [Malvaceae]