Monday, 14 August 2017

Lemon scents

The white flowers of Choisya ternata are, in mid-May, at their finest and are much appreciated by various insects - and by us. I recall recently passing someone as she was trimming a specimen into shape and the pungent smell of citrus fruits pervaded the air. Unsurprisingly it is often referred to as Mexican Orange.
Choisya ternata is generally known as the Mexican Orange.
Byfield, 19 April, 2017
Indeed one only needs to rub or crush one of the ternate leaves to enjoy the fragrance. Not quite lemon and certainly not orange but it comes as no surprise to find that Choisyas are in the same family, the Rutaceae, as these fruits. Ternate, by the way, is the term used to describe compound leaves of three leaflets (in clovers the alternative word 'trifoliate' is used). Monsieur Choisy, the Genevan botanist, would probably, like Claude Aubriet (of Aubrieta fame) have been long forgotten had his name not lived on in a plant. There are five species of Choisya, but the other four species do not appear to be in cultivation.
The ternate leaves of Choisya are quite distinctive.
It would be tempting to assume that all plants carrying a citrus scent are members of the Rutaceae but a moment's thoght shows the idea to be false. 
We have in our back garden a lovely specimen of an Australian 'Bottle Brush' shrub. There are about forty species in the genus but probably the most popular in Britain - and the one we have in our back garden - is Callistemon citrinus and it is just (22 June) coming into flower. Again its leaves release a citrous perfume when rubbed or bruised and its specific name is clearly very apposite. However it is a member of the Myrtaceae family, and is thus related to Myrtle (the shrub, not my great-aunt) and Eucalyptus. The protruding stamens give the 'bottle-brush' appearance and in fact the name Callistemon comes form the Greek kalli - beautiful, and stemon, a stamen. My 1973 edition of Hilliers' Manual of Trees and Shrubs states: 'Only suited to the mildest districts'. But that was then and this is now.
Callistemon citrinus is just coming into flower in our garden.
Stefen Hill, Daventry. 22 June, 2017

We tend not to think of grasses as fragrant plants although, except for the most urban of dwellers, we are all familiar with the fragrance of new-mown hay. This usually betrays the presence of Sweet Vernal-grass, Anthoxanthum odoratum, and the fragrance comes from the presence of a chemical in the coumarin group. Due to its fragrance the seed is often included in seed mixes although really it is not very palatable to livestock. Furthermore it is, in high doses, poisonous, and warfarin is a type of coumarin.
However, as so often, I digress. The grass genus Cymbopogon is generally known as lemongrass and is a true grass in the Poaceae Family with the best-known species being Cymbopogon citratus. It is a tropical grass and therefore not suitable for cultivation in Britain, but I am reliably told that a bunch may be bought from a supermarket. Once home, trim an inch or two from the top of the bunch and place it in a glass of water. If this is kept in a sunny spot growth will recommence after a few weeks with the production of new roots.
Then there is Sweet Flag. This is an aquatic plant, Acorus calamus, and I consider that its leaves, when broken, have a lemony fragrance - in some books it is described as 'smelling strongly of tangerines...'. It is not a British native but may have originated in India; it was introduced into Europe in 1557. It was often grown around country houses - in moats, for example - where the leaves could be gathered and strewn on stone floors. When trodden on they imparted a sweet fragrance to an otherwise malodorous ambience.  At school we were taught the hymn 'All Things Bright and Beautiful', one verse of which* is:
                                           The tall trees in the greenwood,
                                           The meadows for our play,
                                           The rushes by the water,
                                           To gather every day;
The rushes in this case were perhaps, when available,  the leaves of Sweet Flag.
This atypical relative of Lords and Ladies occasionally escaped and has become naturalised here and there as in the canal near Yelvertoft, Northants.
Sweet Flag, Acorus calamus, in the Grand Union Canal at
 Yelvertoft, Northants. 11 June, 2017
I made a pilgramage to Yelvertoft and eventually tracked it down but it was hardly worth the bother. It could only be separated from the Yellow Flag (no relative) with which it grew by its narrower, paler leaves.
It will flower in Britain but apparently never fruits. Together with the Yellow Flag, Iris pseudacorus, grew Branched Bur-reed, Sparganium erectum, an attractive plant but too invasive for all but the largest of ponds. However, lacking a lemon scent this last plant is dragging me away from my chosen topic so I'll call it a day.
Sparganium erectum was growing with the Sweet Flag. Yelvertoft, Nothants.
11 June, 2017

I was planning to conclude this blog with a mention of Lemon Balm, Melissa officinalis. There are a few plants on an old stone wall in Byfield but are such scruffy, unphotogenic specimens that I they weren't worth a picture. In any case, this member of the mint family hailing from south-east Europe,  while having a strong lemon fragrance, is so familiar I decided not to bother.

* Another verse went as follows:
                                        The rich man in his castle,
                                        The poor man at his gate,
                                        God made them high and lowly
                                        And ordered their estate.

We all sang it lustily, thus establishing our position in society, the Church doing its bit to keep the aristocracy firmly where God apparently intended them to be. (The French and the guillotine saw it a tad differently.)

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