California flannel bush, Fremontodendron californicum, Malvaceae

Until the harsh winter of 2009-10 I had a 3m. tall specimen of this lovely Californian shrub growing in my back garden, but sadly the severity of that winter killed it and I haven't yet got around to planting another. It comes from the foothills of the Sierra Nevada, thriving in nutritionally poor soil - which explains why it did do well when it was rooted close to my leylandii hedge, in a very dry spot where nothing else will grow. It's also a good wall shrub, doing well in the rubble around the foundations of a house and trained against a south-facing wall.

The flowers are interesting because, like those of hellebores, the parts that look like petals are actually the sepals - there are no true petals.

It's a very prolific producer of nectar (you can see nectar drops glistening in the image above) so bumblebees love it. 


You do need to be careful when you prune the plant though, because the densely hairy stems and leaves (which account for its name of flannel bush) can cause skin irritation. The cultivar that's most often sold in Britain is usually labelled California Glory.


The plant has traditionally been classified in the family Sterculiaceae, but modern phylogenic studies by the Angiosperm Phylogeny Group, based on DNA sequence data that gives a more accurate reflection of evolutionary relationships, place it in the mallow family - the Malvaceae. Gardeners, and sometimes even professional botanists, often deplore the way in which plant scientific names and classification change so often but they shouldn't - it reflects the fact that someone, somewhere is still taking an interest in the world's flora and that traditional taxonomic botany isn't totally moribund in universities.


Fremontodendron, also know under the synonym of Fremontia, was first discovered by General Fremont near Sacramento in 1846 and was named after him - you can read an account of the colourful life of this soldier, explorer, anti-slavery campaigner, politician and plant collector here.  

Cocao,Theobroma cacao,Malvaceae

I like a nice cup of cacoa - and this is where it comes from. This is the flower of cacao, Theobroma cacao, source of chocolate. These flowers - only about a centimetre across - are pollinated by small insects - notably midges - and then the cacao pod develops (see below).

The tiny cacao flowers are produced in large numbers and are unusual in that they sprout directly from the bark of the tree - a botanical trait known as cauliflory. The plant was formerly classified in the family in the family Sterculiaceae but more recent systematic research has reclassified it as a member of the mallow family. It originates from the foothills of the equatorial Andes and is thought to have been first domesticated 3000 years ago in Central America, where it became the sacred beverage plant  of the Mayans, who believed it was a gift from the gods - a historical link commemorated in the Latin name that Linnaeus bestowed on the plant - Theobroma literally means 'food of the gods'. The Aztecs used cacao beans as a form of currency. 

To produce chocolate the cacao pods are split open and the seeds are extracted from the pulp, then allowed to ferment for several days and then roasted (when the chocolate flavour develops), then ground into a powder. The highest-valued Criollo cacao has relatively low levels of bitter substances but cacoa powder is usually mixed with milk to offset the bitterness. About 3.7 million tons are produced annually to satisfy chocaholic cravings, much of it in West Africa, but about 30 per cent of the crop is lost to pests and diseases. It's hoped that the recent sequencing of the cacao genome will speed-up the selection of disease resistant varieties.

This gent - Sir Hans Sloane, 1660-1753, commemorated with this statue in Chelsea Physic Garden , of which he was patron - is credited with bringing cacao to Britain from Jamaica.  Sloane was a physician and was interested in its medicinal properties but found that it was far more palatable if mixed with milk, inventing a patented recipe for milk chocolate that was eventually acquired by Cadbury. The original Cadbury's chocolate wrappers carried the inscription Sir Hans Sloane's Milk Chocolate prepared after the original recipe.

Sloane's belief in the medicinal properties of chocolate have been echoed for over a century in this illustration on the tin of Droste's cacao, a Dutch brand - where a nurse is shown delivering the drink to the patient. Notice how the image on the tin is repeated in the tin she is carrying on her tray - this cunning advertising image reinforcement, of an advert within an advert, has become known as the Droste Effect.

Sparmannia africana, African Hemp

All plants are capable of gradual movement as a result of slow growth, but relatively few species can make the kind of rapid movements that we tend to associate with animals. The Venus fly trap Dionaea muscipula and the sensitive plant Mimosa pudica are the two species with rapid leaf movements that are most familiar but another fast-mover is African hemp Sparmannia africana. If you gently brush the cluster of golden stamens in the centre of the flower nothing happens for a second, than they move outwards, away from the stigma. The time delay between the photo above and that of the same flower whose stamens have been brushed, below, is about five seconds and you can easily see how the stamens have spread apart.

Presumably this is some kind of mechanism to aid pollination, although how it would do that isn't obvious. Similar stamen movements occur in Mahonia and Berberis flowers, although in those cases the stamens move rapidly inwards when they are stimulated.

Sparmannia africana comes from South Africa and makes a very fine house plant - if you have room for it. My plant grew too big for our conservatory and is now in Durham University Botanic Garden, where it has reached about three metres in height and is currently flowering and setting seed.