Notes and Queries

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What are the black flies with dangling legs that are common at the moment? πŸ†•

From about the end of April, throughout May, you are likely to encounter shiny black files with prominent dangling back legs. The flies, often in large numbers, tend to hover at about head height, rising up and down slowly. Whilst they might be annoying, they don’t bite or sting.

Photo credits: Entomart, Frank Vassen

The flies are male St. Mark’s flies, also called hawthorn flies (Bibio marci). The common names come from the time of year when the flies emerge; St. Mark's day is 25 April, and hawthorn (Crataegus spp.) flowers in early May,

Male and female flies look quite different; males, the ones you see flying slowly, have very large eyes that are adapted to looking for females on the ground whilst, with a separate connection to their brain, monitoring their hovering position. The females by contrast, have very small eyes,

The adults feed on nectar and are important pollinators for fruit trees, though they only live as adults for about a week. The majority of the flies' lifecycle is spent as larvae in the soil, where they feed on rotting vegetation and roots.

Know your carrots: Poisonous plants of the carrot family

The Apiaceae (formerly Umbelliferae) is a large family of aromatic flowering plants commonly known as the carrot family. It contain both edible and deadly species which can be difficult to distinguish from one another.

The edible members of the Apiaceae include the herbs and vegetables: angelica, caraway, carrot, celery, coriander, dill, fennel, parsley and parsnip. It also includes edible wild species that some people forage*, such as alexanders (common near the Norfolk coast), cow parsley and wild carrot.

However, two of the most poisonous plants in Britain, hemlock (Conium maculatum) and hemlock water-dropwort (Oenanthe crocata) look very like some of the species that are foraged.

Hemlock (Conium maculatum)

This is the plant that was used to execute the ancient Greek philosopher Socrates.

An upright plant, 1.5–2.5 m (5–8 ft) tall, hemlock can be distinguished by the distinctive and unpleasant, mousy smell of its foliage. It has a smooth, green, hollow stem, usually spotted or streaked with red or purple on the lower half of the stem. All parts of the plant are hairless. Its leaves are finely divided and large, and its flowers are small and white and appear in umbrella-like clusters. It is relatively common in Norfolk.

⚠️ Hemlock looks very like the wild carrot plant (Daucus carota).

🌲 Coniferous trees of the genus Tsuga, are also often confusingly referred to as hemlock (eg. western hemlock Tsuga heterophylla), The common name comes from a slight similarity in the leaf smell. Tsuga trees aren't poisonous or related to Conium maculatum.

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Hemlock Water-Dropwort (Oenanthe crocata)

Hemlock water-dropwort is a hairless perennial growing up to 150 cm tall with hollow, cylindrical, grooved stems up to 1 cm across.

All parts of the plant are toxic. The leaves and stems look rather like parsley or alexanders and the leaves smell like parsley or celery. The highly toxic roots look and smell like parsnips. It is not often found in Norfolk.

πŸ˜† A Sardonic Smile. The word sardonic has is roots in pre-Roman Sardinia where ingesting the sardonion herb, hemlock water-dropwort, was used in ritual killings. As well as stopping the victims heart, the poison would also act on facial muscles, drawing the face into a rictus grin, or sardonic smile.

Ref: Wikipedia, Sardonicism

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Phototoxic Skin Inflammation

Several members of the carrot family, Apiaceae, produce phototoxic substances that sensitise human skin to sunlight. Contact with these plants, followed by exposure to sunlight, can cause serious skin inflammation (phytophotodermatitis) . Of these, the most serious are the hogweeds - see the giant hogweed section of the local citizen science survey. However the sap of normal garden parsnip plants (Pastinaca sativa) can also cause phytophotodermatitis.

There is no good scientific evidence that the potentially fatal toxins in hemlock (coniine) and hemlock water-dropwort (oenanthotoxin) are toxic through skin contact, though there is anecdotal evidence of some absorption of toxins via skin and inhalation. It is good practice to only handle these very poisonous plants with gloves.

*⚠️ Never forage for members of the carrot family unless you are absolutely 100% sure of the species.

Jeff

What is the difference between bulbs, corms, tubers and rhizomes?

Bulbs, corms, tubers, and rhizomes are underground storage structures that can develop into new plants under favourable conditions. These underground structures are all β€˜geophytesβ€˜.

The name of a particular geophyte indicates which part of the plant has evolved into the storage structure:

  • Bulbs consist of modified leaves, which store nutrients. Eg. daffodils, hyacinths, alliums.

  • Corms are swollen stem bases. Eg. gladiolus, freesia.

  • Tubers are thick underground stems. Eg. potato, .caladium, cyclamen, anemone, Jerusalem artichoke.

  • Rhizomes are swollen stems that grow horizontally. Eg. iris, lily-of-the-valley, canna.

Jeff

Is it safe to touch ragwort with bare hands?

There is frequently repeated gardening advice that you should wear gloves when touching or pulling ragwort as its toxins are readily absorbed through the skin, causing potentially fatal liver damage. This is a myth:

"Ragwort poisoning takes place in the digestive system. In the plant, pyrrolizidine alkaloids are stored in their non-toxic form. Only if these substances end up in the digestive system, they will be converted into their toxic form. There is no scientific evidence that skin contact leads to the conversion of non-toxic alkaloids into their toxic form. Some people experience an allergic reaction after skin contact (compositae dermatitis), but this response is cause by sesquiterpene lactones rather than pyrrolizidine alkaloids. These sesquiterpene lactones are common chemical compounds of members of the Sunflower family" (source: ragwort.org)

There is also a great deal of misinformation circulating about a legal obligation to destroy ragwort on one's land (not-true). Ragwort (Jacobaea vulgaris) is however the most important food source for the cinnabar moth (caterpillar picture below), whose numbers have been declining. In fact ragwort is a food source for at least 77 insect species in the UK. Over half of these use ragwort as their exclusive food source, and 10 of these insect species are rare or threatened.

See ragwortfacts.com and Friends 0f the Earth for more on toxicity.

Jeff

Is it safe to touch monkshood with bare hands?

Unlike ragwort, there is scientific evidence that the toxins in aconites, commonly known as monkshoods (Aconitum species) can be absorbed by the skin. It is a good idea to wear gloves when handling monkshood, even though the risk of absorbing sufficient alkaloid to cause ill-effects is low and only the roots have sufficient concentration of toxins to be a concern. All parts of the plant are poisonous.

Winter aconite (Eranthis hyemalis), whose yellow flowers appear at the same time as snowdrops, is not a member of the Aconite genus, despite its common name. Like many member of the buttercup family, it is however poisonous, though not to the same degree as the true aconites..

Reference: Aconite poisoning following the percutaneous absorption of Aconitum alkaloidsJeff

About tomatoes...

  • There are over 10,000 varieties of tomatoes and over 160 million tonnes of tomatoes are produced each year.

  • Tomatoes contain seeds and so are classified as a fruit, not a vegetable. Botanically the tomato is a berry (as are avocados, bananas, cucumbers and pumpkins).

  • The binomial name for the tomato is Solanum lycopersicum (syn. Lycopersicon esculentum). Lycopersicum means wolf (lycos) peach (persicum). And 'peach' is itself derived from mālum Persicum, the Roman name for the fruit, meaning Persian apple.

  • It is best not to refrigerate tomatoes as this can harm their flavour; tomatoes stored in the fridge tend to lose their flavour permanently. Tomatoes keep best unwashed at room temperature with the stem down; the inversion can keep them from rotting longer.

Jeff

King Alfred's Cakes

These smooth hard structures were spotted in Mileham growing on a dead ash branch. They are the fruiting body of Daldinia concentrica and commonly known as King Alfred’s cakes; they do look like a burnt bun.

Also going by the common name of Coal Fungus, the 'cakes' have long been used as firelighters, with evidence from 7000 years ago of their use as kindling.

Jeff