Thursday, 31 August 2017

Can't be bothered

Today I paid a visit to Kentle Wood but decided, for perhaps the first time, not to produce a blog about it. I admit there was quite a lot to see, with Keats' 'Season of mists and mellow fruitfulness' almost upon us but there it is. I can almost hear the anguished, nay pitiful, groans of my readers as my message sinks in. 'Are we to end August without Tony's words of wisdom inane comments?' they cry. But I will not be moved.

After all, the hips on the wild roses...
Rose hips in Kentle Wood, Daventry. 31 August, 2017
The raven-black fruit on the Dogwood, Thelycrania sanguinea...

Dogwood with berries. Kentle Wood, Daventry. 31 August, 2017
and the glossy scarlet berries on the Bittersweet, Solanum dulcamara...

Woody Nightshade (Bittersweet). Kentle Wood, Daventry.
31 August, 2017
were failing to tempt any visitors so there seemed little incentive to put finger to keyboard. Even the Speckled Wood butterfly, posing so nicely, turned out to have a damaged wing.
This Speckled Wood was coping admirably with its disability.
Kentle Wood, Daventry. 31 August, 2017
As for the Greater Plantain, Plantago major, aka the Rat-tailed Plantain, regarded as 'one of the most abundant, widespread and valuable of all the temperate zone medicinal herbs' ('Wonderful Weeds', Madeline Hartley, 2016) it failed, for all its beauty, to fire me with any enthusiasm.
Anyway, blog or no blog, I was pleased to record Eristalinus sepulchralis, a distinctive fly with black speckled eyes.

Who could fail to be enchanted by the beauty of Greater Plantain?
Kentle Wood, Daventry. 31 August, 2017
So I returned home, there to be awestruck again by our entry in 'The World's Most Knobbly Potato' Competition, lifted from our allotment earlier today. I'm afraid this condition tends to be the consequence of uneven watering. Well, its has been an odd sort of summer.

Wednesday, 30 August 2017

St Giles' Churchyard

Back in 1985 Francis Greenoak published her book God's Acre (not to be confused with Erskine Caldwell's lurid novel God's Little Acre). It took a look at the wildlife of the British churchyard and helped to remind people what vital oases these areas are. Thirty years later and their importance is even greater; they act as a Noah's Ark for many scarce and vanishing species.
Perhaps Francis Greenoak's main concern was the village churchyard but yesterday, while Chris was receiving her regular treatment at Northampton General Hospital, I took a stroll around the churchyard of the nearby St Giles' church, in the heart of Northampton, and it struck me as how important the area is, not just for wildlife but as a temporary escape for shoppers, office workers and the like, who just need somewhere to unwind for perhaps fifteen minutes or so. Today, in warm sunshine, many were doing just that.
I cannot deny that I was there to see what wildlife had found sanctuary and I was both pleased and disappointed. Disappointed in that, although several fine trees stand in the grounds only one, holly, is a British native, considerably limiting the potential for invertebrates in particular.
The leaf miner, Phytomyza ilicis, on holly. St Giles churchyard,
Northampton. 29 August, 2017
Only one organism appeared to be making use of the holly and that was the leaf miner Phytomyza ilicis, an insect so common that I would have been astonished if it had not been there. To be fair the flowers are much visited by insects for pollen and nectar whilst the berries are appreciated by many birds.
In the open country roadside and neglected fields are currently ablaze with common ragwort. Here in the town it's place had been taken by Oxford Ragwort, Senecio squalidus, and its flowers were receiving quite a few visitors, like this hoverfly, Eristalis arbustorum.
Eristalis arbustorum on Oxford Ragwort. St Giles churchyard,
Northampton. 29 August, 2017
Also on the Oxford Ragwort was a plump but rather nondescript caterpillar. I'm no lepidopterist but I've a suspicion that it is the Heart and Dart, Agrotis exclamationis (I ruled out a similar-looking species found on lichens in Patagonia). The black lump on the back is a lump of frass or, to use the correct scientific term, poo.
Heart and Dart? Feeding on Oxford Ragwort in St Giles churchyard,
Northampton. 29 August, 2017
Speaking of frass, a nearby sycamore leaf was displaying a rather distinctive mine. It has been formed by the larva of the Barred Sycamore Pigmy Moth, Stigmella speciosa. The egg hatched in the bottom right hand corner and worked its way towards the top left, the mine widening as the larva grew. It has left a distinct dark line of frass on its journey.
The mine of Barred Sycamore Pigmy Moth on a sycamore leaf.
St Giles churchyard, Northampton. 29 August, 2017

The moth was first found in Britain in 1914 and has slowly spread northwards although it is still scarce in the northern parts of its range.
So, there was more to St Giles churchyard than street pigeons and, with all these eggs on a sycamore leaf, who knows what is yet to come?
Free range eggs on a sycamore leaf. St Giles churchyard, Northampton.
29 August, 2017


Monday, 28 August 2017

Unfortunate caterpillar

I took a stroll around Byfield Pocket Park earlier today. However, the main item of interest was noted just before I entered, for on a 'Lombardy' Poplar a short distance away was the caterpillar of a moth. Identifying it was not a problem for it was clearly a Poplar Grey, Acronicta megacephala. But what had happened to it?
Poplar Grey moth - but what are the egg-like objects?
Byfield, Northants. 28 August, 2017
It was still alive - just - but was surrounded by about thirty 'eggs' (not all can be seen on the photograph) and they may have belonged to a tachinid fly, several species of which are known parasites of caterpillars. The sheer mass of the eggs would surely rule out the work of a single fly so were more than one of these parasites involved? Or indeed were they tachinid eggs at all? The internet is usually helpful on these matters but gave me only a few clues and I remain puzzled. Nor, with arms at full length, could I obtain a satisfactory photograph so I brought the leaf home. Perhaps I may be able to rear some specimens.

A slightly better look.

The day was very hot and sunny but not a great variety of insects was observed. There was plenty of Bush Vetch, Vicia sepium, in flower but few bees were exploiting it. In terms of colour this species has quite variable flowers and these were of a rather sombre slate-blue.
Bush Vetch was receiving few visitors. Byfield Pocket Park.
28 July, 2017

There wasn't really a lot else: no 'oohs' or 'ahs', and the best I could come up with was a neat little trio of galls on a Grey Willow leaf. They were the work of a sawfly, Pontania proxima, a common and widespread species. I have never knowingly seen an adult of this species, but then again, sawflies aren't my field.
Galls caused by the larvae of a sawfly, Pontania proxima.
Byfield Pocket Park. 28 August, 2017
So I set off home, lingering only for a moment as I photographed a sinuous leaf mine on Hogweed. It was another exceedingly common insect, Phytomyza spondylii, and to be honest I simply photographed it because I was too lazy to take out my notebook and write it down. Shameful! But it turned out to be a new record for the pocket park.
The larvae of Phytomyza spondylii have been mining this hogweed leaf.
Byfield Pocket Park. 28 August, 2017

Sunday, 27 August 2017

Frack to bunt

Today was a further meeting of the Northamptonshire Diptera Study Group. Two locations were to be visited - Sulgrave and Helmdon. Sulgrave was first up so, stupidly, I went to Helmdon.
No damage was done really because the weather was glorious and I recorded a large number of spiders and insects (actually, to be honest, only a handful of spiders and harvestmen but lots of insects).
The most obvious spider species was the Four-spotted Orb Weaver, Araneus quadratus.

Araneus quadratus. A female on comfrey. Roadside near Helmdon,
Northants. 27 August, 2017

Currently the females are broadly similar in size to the Garden Cross Spider, Araneus diadematus, but once a female A. quadratus is swollen with eggs, a few weeks time, she will be considerably bigger and at one time featured in The Guinness Book of Records as the heaviest British spider. I accidentally netted a Garden Cross Spider and the photograph allows the similarities and differences to be seen.
Garden Cross Spider. Roadside near Helmdon, Northants.
27 August, 2017
The white cross on the back of A. diadematus is actually formed by cells swollen with guanine, a widespread substance in animals and, to a lesser extent, in plants.
Another animal, this time not a spider, was not seen until I discovered it in my net. This was the Bishop's Mitre Shieldbug, Aelia acuminata, and it was not surprising that I hadn't spotted it for it has the shape and colour of a dried grass head.
Bishop's Mitre Shieldbug. Roadside near Helmdon,
Northants. 27 August, 2017

With the next sweep of my net I secured - deliberately this time - a female Oak Bush Cricket, Meconema thalassinum. It is a widespread species with the long female ovipositor typical of the genus. Unfortunately all the specimens in the net proved quite difficult to photograph, while another species, Roesel's Bush Cricket, wouldn't allow a photograph at all but fortunately it is a very distinctive insect. Catching one was quite unnecessary. 
Oak Bush Cricket from roadside nr Helmdon, Northamptonshire.
27 August, 2017
The roadside verges supported a rather good flora with Ragwort, Jacobaea vulgaris, quite prolific and attracting many insects, particularly hoverflies. It is a plant with a bad reputation but even less welcome, particularly along watercourses, is Indian (Himalayan) Balsam, Impatiens glandulifera.
Indian Balsam in damp ditch near Helmdon, Northants.
27 August, 2017
Here it seemed to be content with a damp ditch and formed only a small patch, unlikely to pose a problem, but in some areas such as along the River Nene east of Northampton, it is a rampant weed and it is illegal to introduce it into the wild. It must be admitted that it is a beautiful plant, and bees love it although the cloying fragrance is rather odd.
The insect life was prolific and although I avoid taking specimens unless absolutely necessary (probably letting 99% go free) I still set off home, passing the rest of the recording group going in the other direction, with much work ahead of me.


Thursday, 24 August 2017

Hospital visits: a phenological diary

My regular visits with Chris to Northampton General Hospital have allowed me to observe the changes in the hospital grounds over the months, for I generally have between one and two hours to stroll around while she is receiving treatment. To regard my observations as constituting a 'phenological diary' is rather overstating the case but the seasonal changes have been interesting.
Every year, towards the end of summer, people are surprised to see large orb webs appear in their gardens, with correspondingly large specimens of the Garden Cross Spider, Araneus diadematus, in occupation. Of course they have been there for several months but are relatively inconspicuous when at an immature stage. 

A Garden Cross Spider wraps up a greenbottle. Northampton General
Hospital grounds. 24 August, 2017
Just as I was passing a tangle of bindweed a greenbottle fly blundered into a web; a large female promptly dashed out and began to swathe the victim in silk. The spider looked quite plump and may have been gravid; she will lay her eggs in a silken cocoon and then die within a few weeks.

For some weeks I have been observing a plant of Deadly Nightshade, Atropa belladonna, as it produced its flower buds, bloomed and developed green fruits. Today I made my pilgrimage expecting to find ripe, purple fruits; alas, it had been cut to the ground and all the top growth was dead. The species has occupied the site for many decades and I am confident it will be back.

Traveller's Joy, aka Old Man's Beard. Northampton General Hospital.
24 August, 2017
Many of the shrubs in otherwise tidy borders have become festooned with Traveller's Joy, Clematis vitalba. The plants are now in flower but have also now produced their white, feathery achenes, thus justifying the plant's alternative name of Old Man's Beard

The same species in flower scrambling over a Cherry Laurel shrub.
Northampton General Hospital. 24 August, 2017
One or two flower beds are difficult to reach and specimens of Canadian Fleabane, Conyza canadensis, have taken advantage of the neglect to send up their tall panicles of flowers. They would not be planted deliberately as their flowers are very undistinguished.
The tall spires of Canadian Fleabane in a neglected border.
Northampton General Hospital. 24 August, 2017
Although it is a native of North America it has been known in Britain from the 17th century but seems to have flourished on ruins and waste ground following air raids in World War Two. Its seeds are borne on 'parachutes' and are quick to colonise any open, sunny spaces.
The flowers of Canadian Fleabane rarely feature in floral bouquets!

I'll be back again at the hospital soon so watch for further exciting developments!

(I have just brought to mind the words of my maternal grandmother. Hailing from Earls Barton she had a strong Northamptonshire accent so that words like 'cross' would be pronounced as crorse; similarly a hospital was a horspital. Sometimes it sounded alarmingly like 'horse piddle'. 'Air Ida's bin under the doctor at the horse piddle,' she would tell a startled audience.)

Wednesday, 23 August 2017

Byfield Pocket Park

The concept of Pocket Parks seems to have originated in Northamptonshire. A piece of unused or otherwise waste land is brought under control and managed, primarily - as I see it - as a refuge for otherwise beleaguered wildlife. 
Byfield's pocket park occupies the site of the village's former railway station and, although some parts of it currently offer little in the way of wildlife habitat, it supports a wide range of species. I had recorded in excess of five hundred species but then, in the process of upgrading my computer, one file was lost. Fortunately the plant list has survived and stands at 125 species, but this list includes ornamental plantings. Undaunted I have started the invertebrate animals again and today I made another visit to do a spot of recording.
Even before I reached the pocket park I paused for a short time to photograph a troop of Honey Fungus, Armillaria mellea. Not only is this very variable species but there are other closely related species so I'm hoping I've got this right. It will be growing on the base of a hidden tree bole but and I was not able to establish what the tree might have been.
Honey Fungus beside a footpath near The Green, Byfield.
23 August, 2017

Anyway, onwards and upwards. Once at the pocket park I made a point of visiting a large oak in a central position. Oaks support an enormous number of insects and other arthropods and always repay close attention. As expected a large number of galls were to be seen. As a child I always found that Oak Marble Galls were the most common. They are the work of a tiny wasp, Andricus kollari, and a close examination of the photograph shows the entrance hole from which the fully-grown wasp emerges.
The Oak Marble Gall is extremely common.
 Byfield Pocket Park. 23 August, 2017
Nowadays, commoner by far, are Knopper Galls formed on the acorns; here the wasp responsible is Andricus quercuscalicis. In some years a tree may hardly have a single acorn undamaged.
The Knopper Gall is ever more common.
Byfield Pocket Park. 23 August, 2017
At this time of the year a close examination of many plants will reveal galls and hawthorn is a case in point. The leaf edges here have been attacked by a mite, Phyllocoptes goniothorax, and although it is a new record for the pocket park it is a very widespread species.
Hawthorn leaves galled by Phyllocoptes goniothorax.
Byfield Pocket Park. 23 August, 2017
The other group of creatures to become obvious at this time of the year are the leaf miners. This very distinctive mine on a beech leaf is the work of  the Small Beech Pigmy Moth, Stigmella tityrella and over the next few weeks I hope to find many other related species.

The larva of the Small Beech Pigmy Moth creates a very distinctive mine.
Byfield Pocket Park. 23 August, 2017
The list of invertebrates has grown and now tops 150 species. But that means there's still an awfully long way to go.

Monday, 21 August 2017

An evening stroll

Today, Monday, 21 August, has been a frustrating day. The BBC weather forecast had suggested that we would enjoy warm conditions with a dash of sunshine thrown in. Well, we got the former but not the latter and it was a very damp, dull and muggy sort of day. It remained that way until well into the evening but, feeling the need to stretch my legs, I took a stroll. But only locally.
Muggy or not, the Eryngium bourgatii in our front garden was attracting many greenbottle flies. A surprisingly large number of greenbottle-like species occur locally - and indeed around most suburban areas. I left them to get on with their nectaring and strolled on. They had almost certainly all been recorded before - several times over.
Greenbottles attend the inflorescences of an Eryngium in our garden.
21 August, 2017
I made for a strip of well-wooded ground separating Christchurch Drive and the A45. The latter is an extremely busy stretch of road and so the trees fulfil the very important function of cutting out most of the noise; life would be miserable for the local residents without it. The commonest trees are ash and field maple, with a few other species thrown in. I was pleased to see that there are plenty of seedlings present.
Seedlings of ash (left) and oak (right) were flourishing.
Christchurch Drive, Daventry. 21 August, 2017
Beneath the trees are logs and old pieces of wooden fencing in a state of semi-decay. It is always worth turning some over and today a Devil's Coach Horse, Staphylinus olens, was present although it scuttled away before I could photograph it. This is one of the rove beetles, of which there are over a thousand species in the U.K. alone. I record only a few of the more distinctive species, but the Devil's Coach Horse is easily the largest common species and its shape and matt-black coloration make it unmistakeable.
Also present were many specimens of the Yellow Slug, Limacus flavus, together with its strings of eggs. This is an extremely common species even in built-up neighbourhoods.

Beneath the gloom of the trees a plank of wood concealed Yellow Slugs.
A string of eggs is to their left.
Replacing the timber I continued to where the trees thinned out to be replaced by grassy sward. The area was made colourful by hundreds of Ragwort plants. John Clare appreciated their beauty, even though he was surely aware of farmers' attitude towards it: 
                                      Ragwort thou humble plant with tattered leaves
                                      I love to see thee come and litter gold...

It is, of course, those 'tattered leaves' that have given Ragwort its name. Lovely though it is, some of its vernacular names relate to its poisonous properties: Mare's Fart, Staggerwort and Stinking Willie are but three of a host of names recorded. As for its Latin name, this has recently changed from Senecio jacobaea to Jacobaea vulgaris. Ragwort causes irreparable liver damage to horses and cattle but is generally avoided by stock. Nevertheless the Ragwort Control Act 2003 was introduced to try and suppress it.

Ragwort has flowers of brilliant gold and here is flowering beside the A45.
Daventry, 21 August, 2017

Entomologists certainly appreciate it as it attracts a large range of insects and this evening I spent some time checking the flower heads. Many hoverflies of at least four species were present including this female Drone Fly, Eristalis tenax.

The Drone Fly is one of the larger of our native hoverflies.
Daventry, 21 August, 2017 
Be that as it may, my evening stroll failed to come up with anything remarkable and I must hope that there are surprises in my pot of specimens to be examined later.

Postscript  I found that I had secured a specimen of the small brown lacewing,
Sympherobius pygmaeus; it may be the first record of this species from Northants.


Thursday, 17 August 2017

Oh I do like to be beside the...canal

I sallied forth yesterday intending to do some recording at the northern part of Kentle Wood. At this end the woodland meets the A45 so the plan was to drive along the road and stop at a convenient point. There was none. I drove on and on without finding anywhere to park and soon found myself in Braunston. I capitulated - I know when I'm beaten - and settled for a stroll along the Grand Union canal near to the very busy Braunston marina.
The scene was colourful as I made my war between craft of various sizes, styles and colours (yes, I should have taken a few pictures) and the day had steadily improved from a showery morning to a lovely afternoon.
It is clear why gardens are so important to many insects and why we are encouraged to grow plenty of nectar- or pollen-yielding plants because the canal banks did not have a lot to offer.
There was a small clump of Orange Balsam, Impatiens capensis, a garden escape from North America. This relative of 'Busy Lizzies' is a very attractive plant to look at but although I observed it on and off for an hour or so it received no visitors.
Orange Balsam, frequent along canals. Braunston, Northamptonshire.
17 August, 2017

Fortunately there were several plants of Wild Angelica, Angelica sylvestris, to provide a re-fuelling point for insects. (It is not to be confused with Garden Angelica, Angelica archangelica, which is native to some parts of northern Europe but is an escape in Great Britain. and not found in Northamptonshire.) Wild Angelica is common throughout our county in damp pastures and beside watercourses. G.Claridge Druce, in his 1930 Flora of Northamptonshire, seems to have referred to this species as 'Keck' although I have only ever heard the name applied to Cow Parsley, Anthriscus sylvestris. This latter plant will attract small insects but Wild Angelica is visited by a good range of larger flies and bees. 
Wild Angelica saved my day by attracting insects. Braunston, Northants.
17 August, 2017
Today these included a handsome female hoverfly Myathropa florea, a rather convincing wasp-mimic. It is common but nevertheless pleasing to see. I am surprised that it has not acquired a common name.
Myathropa florea on Wild Angelica. Braunston, Northants.
17 August, 2017
Several other hoverflies were present although nothing other than common species. The photograph shows a relative of Myathropa, Eristalis arbustorum, also a female and probably a mimic of the hive bee.
Eristalis arbustorum on Angelica. Braaunston, Northants.
17 August, 2017
One butterfly - a Meadow Brown, Maniola jurtina - called in but couldn't be persuaded to open its wings for a photograph. It made use of the one tiny bit of Yarrow, Achillea millefolium.
A rather pale Meadow Brown on Yarrow.
Braunston, Northants. 17 August, 2017
Only one other plant appeared to be attracting insects and that was Hedge Woundwort, Stachys sylvatica. It had ceased flowering but a Woundwort Bug, Eysarcoris venustissima, was delving into a group of calyces. Shieldbugs pass through a number of stages (instars) and this was a last-instar specimen, in other words it was in its fifth stage and the last one before adulthood.
Woundwort Shieldbug on its foodplant, Stachys sylvatica.
Braunston, Northants. 17 August, 2017
In terms of variety not many insects were recorded but most if not all will be the first records for the area, helping us to more fully understand the distribution and needs of our insect species. And I secured a specimen of a curious little orange-red beetle to be identified later under the microscope*. Not a bad day.

* It turned out to be Neocrepidodera transversa, one of the flea beetles. (I know you were desperate to find out!)

Tuesday, 15 August 2017


A couple of days ago the total number of organisms I had recorded from Kentle Wood was 499. There is little point to the simple compilation of lists, but over the decades most naturalists have produced lists of this, that and, sometimes, the other. Those dating back over fifty years or so are valuable in demonstrating the enormous changes that have taken place subsequently.
Anyway, within a few minutes of arriving today I recorded my 500th species - an Angle Shades moth, Phlogophora meticulosa, in the form of a caterpillar beaten from a willow tree.
The larva of the Angle Shades Moth. Not easy to spot among the greenery.
Kentle Wood, Daventry. 14 August, 2017
The only surprise is that I hadn't recorded it before, as it is exceedingly common.
The trees bordering the rides are now heavily laden with foliage, in some places creating a heavy shade. A jay screamed out as I wandered along. Why are these brightly-coloured crows so difficult to spot?
Woodland rides are now quite shady in places.
Kentle Wood, Daventry. 14 August, 2017
In more open spaces, where the sun can get to ground level, thistles are much in evidence. The commonest species by far is Creeping Thistle, Cirsium arvense, a serious pest of agricultural land. In its defence it attracts hordes of insects and it is always worth spending a few minutes on a large clump.
The gall of Urophora cardui. Quite unmistakeable.
Kentle Wood, Daventry. 14 August, 2017
The stems are commonly galled by the tephritid fly, Urophora cardui, and a gall I noticed today was probably the largest I have ever seen, approaching golf-ball size. Working my way steadily along I noted a few interesting insects for closer examination later.

It turned out that I had found two more species:

Panorpa germanica - a scorpion fly                          501
Sitona puncticollis - a moderately common weevil   502

I had also taken home a pot of spiders. Surely, I thought, there will be something a little out-of-the-ordinary. But no, that was it for the day.
I'll eventually pass on my list to the Woodland Trust and the local Wildlife Trust to provide a baseline of species for future naturalists.

Tony White    E-mail:

Monday, 14 August 2017

Scented Mayweed

Anyone who has strolled along a footpath near a cornfield or simply on rough ground will be familiar with Scentless Mayweed, Tripleurospermum maritimum. Its Latin name suggests that it grows beside the sea and the subspecies maritimum does indeed favour rocky or shingly areas beside the sea. However the plant seen inland is usually subspecies inodorum, and it is, again as the name indicates, unscented.
Earlier today, as I strolled down to the local pharmacist's to collect my d.t.p. (dicky ticker prescription) I noticed some of the slightly less common Scented Mayweed, Matricaria recutica, growing beside the footpath. Although not quite as common as its scentless cousin it may also be abundant in cornfields if they are untreated. It can be recognised with ease if - as is often the case - the ray florets are drooping.
Scented Mayweed beside the London Road, Daventry.
14  August, 2017
An old  name is Wild Camomile and an alternative Latin name was Matricaria chamomilla.  It has in the past been used as an alternative to the true Chamomile, Chamaemelum nobile, as an aid to sleep. It is also claimed to have bactericidal properties.
As the flowers age the ray florets tend to droop.
It was once popular with herbalists when it was usually, for no apparent reason, known as German Chamomile.  In one of my books I learn that it 'acts as a tonic upon the gastro-intestinal canal'. It is also valued in the treatment of earache, neuralgic pains, stomach disorders and 'infantile convulsions'. Cor blimey!
I'll never walk by it again without an act of obeisance.

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.)