Your umbel servants
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Ask a child to draw a flower and odds are you’ll end up with
something round, multi-petalled and daisy-like. That’s interesting because
daisies are not really single flowers at all, but compound heads of many small
flowers joined together. Another plant family, just as common as the daisies
and with many more ‘useful’ representatives also bears heads of massed tiny
flowers. Although its members are nowhere near as universally recognisable as
daises, the flowers of the Umbelliferae or Apiaceae are,
nevertheless, very distinctive.
The flower head is a special type of inflorescence known as
an umbel, from which the family takes its name. Umbels are flat-topped flower
heads in which all the flowers are borne on individual stems (pedicels) that
arise from the same point at the top of the flower stem — rather like the
canopy and strings of a parachute. Sometimes the heads are branched, but the
individual pedicels of each head always radiate from a common point. While it’s
not that easy to describe, the effect is immediately obvious when looking at an
umbel.
Usually, the petals of the individual flowers are tiny,
though not insignificant because they’re often brightly coloured. The blue lace
flower (Trachymene caerulea) of Western Australia, which is a biennial
frequently treated as an annual, has some of the brightest flowers and largest
petals in the family and its pale blue colouring is certainly distinctive. In
some cases the flowerheads are backed by coloured bracts that give the head
more colour and a rather papery look and texture. Astrantia and Eryngium
are good examples of bracted umbels.
Many common herbs and vegetables are umbels. Indeed, the Umbelliferae
is sometimes known as the carrot family, after its best known member: the
edible carrot (Daucus carota). Of course, it could also be called the
parsley, fennel or angelica family and remain almost as widely recognised.
The Umbelliferae is a family of some 420 genera encompassing over 3000 species. Although it’s mainly a family of the northern temperate zones, representatives occur worldwide. Several members of the family occur in New Zealand and they’re particularly common in subalpine areas. There, among the tussocks, gravel and low vegetation, the spear grasses or spaniards (Aciphylla spp.) and the very carrot-like Anisotome and Gingidia species are among the more dominant plants. And higher up on the scree slopes of the South Island mountains live the grey-leaved Lignocarpa species.
In addition to the huge range of herbs, which may be annual,
biennial or perennial, the family includes a few shrubs and trees. Most are
plants that grow in everyday conditions — moist yet well-drained soil — but a
few prefer boggy conditions while others are succulents or tolerant of very dry
conditions. So, as with most plant families of this size and distribution,
there’s an umbel for just about anywhere in the garden.
Because of their wide range of habitats, it’s probably
easiest to review the umbels by looking at various garden settings and the
plants best suited to them. Some can do double duty, say in both the herb
garden and the perennial border, so don’t feel limited by convention when
deciding how to use the plants.
Vegetable garden
Carrots, parsnips (Pastinaca sativa), and celery (Apium graveolens var. dulce) are garden staples that scarcely need describing. While able to be grown over most of the country, they can pose a few cultivation difficulties, such as controlling carrot rust fly on carrots and parsnips and keeping celery rust at bay.
However, provided the soil is deep enough to allow the roots to develop and you sow fresh seed for good germination rates, carrots and parsnips aren’t too tricky. Of course, southern gardeners will say that no North Island-grown parsnip could possibly match one touched by a southern frost. (And they’re right.)
Celery’s less common swollen-rooted form, celeriac or turnip-rooted celery (A. g. var. rapaceum), is an undemanding plant that tolerates most soils. It matures in the autumn but can be left in the ground and used over winter.
Herb garden
Umbellifers dominate in the herb garden, not just because of their numbers, but also with their size. Fennel (Foeniculum vulgare), dill (Anethum graveolens), lovage (Levisticum officinale), sweet cicely (Myrrhis odorata) and the various species of Angelica all tower above the smaller thymes, mints and soapworts.
In addition to their culinary and medicinal uses and flower heads, most of which develop in late summer and autumn, they are useful for their different and distinctive leaves: fine and feathery for fennel; light green and celery-like with lovage; and fern-like fronds of angelica.
On the subject of angelica, although the glossy-leaved A. pachycarpa is often seen in herb gardens, the species used for making candied angelica is A. archangelica. Also known as archangel or wild parsnip, it is a Eurasian native that can reach as much as 2m tall when in flower.
The smaller umbelliferous herbs, especially parsley (Petroselinum crispum), chervil (Anthriscus cereifolium), coriander (Coriandrum sativum) and caraway (Carum carvi) are remarkably easily grown and trouble-free once established. They are often sold ready-grown in nurseries, but take care to choose plants that are not too advanced or they may suffer with transplanting. Aniseed (Pimpinella anisum) too, has no special cultivation requirements, though it is only an annual.
Sunny perennial border
Along with the herb garden, the perennial border is where
umbellifers really shine. Because of their size, most are best placed to the
back of the border where they won’t overpower smaller plants. Their bold forms
ensure they’re unlikely to be lost even with other growth in front of them.
Many umbellifers come from areas with a continental climate:
very hot summers and very cold winters. To survive such conditions they require
extreme hardiness. Consequently umbellifers include some of the toughest plants
that can be grown in the perennial border.
The largest and most vigorous are black parsley (Melanoselinum
decipiens), which has strong woody stems, large pinnate leaves and 20–80cm
wide heads of pink flowers; and giant hogweed (Heracleum mantegazzianum),
an herbaceous perennial that can reach 5m tall in the space of one growing
season. Black parsley is a native of Madeira and an exception to the hardiness
rule. It tolerates moderate frosts, but nothing too severe or too regular.
Giant hogweed, which sometimes behaves as a biennial, is extremely tough and
has huge wheel-like heads of white flowers. The smaller 1.5–2m tall Heracleum
lehmannianum is better suited to most gardens.
Foliage is one of main attractions of the angelicas. It can
be light or dark, matt or highly glossy depending on the species. My favourite
is the imposing deep green-leaved Angelica gigas, but it’s not just a
foliage plant — its flower heads and stems are reddish-purple and can grow to
as much 2.5m tall — a spectacular sight in late summer.
Great burnet saxifrage (Pimpinella major) and burnet
saxifrage (Pimpinella saxifraga) both grow to around 1.2m high when if
flower. While their flowers, which are very abundant, are usually white to pale
pink, P. major also occurs in a deep pink form called ‘Rosea’.
The sea holly genus (Eryngium) includes well over 200 species, many of which are very distinctive plants. Their often spiny leaves (hence the holly name) and silvery purple flowers give them a rather thistle-like appearance, but it would be a very sophisticated thistle that could approach the beauty of an Eryngium. My favourite, E. giganteum, has bright green foliage and grows to 1.5m tall. Because of the way the plant ages through green and grey-green to an ethereal silver-white, it is sometimes known as Miss Willmott’s ghost (after British gardener Ellen Willmott).
Other attractive species include the heavy flowering E. caucasicum (syn. E. caeruleum) and E. heterophyllum, which forms a neat clump of basal leaves topped with a vase-shaped spray of flower heads.
The true sea holly (E. maritimum), a native of coastal Europe, has silver-grey foliage. This is also a feature of Eryngium proteiflorum; the silver leaves and bracts of which have a dull metallic sheen.
Smaller still and very popular a few years back, the
masterwort genus (Astrantia) includes several species with conspicuous,
often brightly coloured, bracts. There are many cultivars, particularly of A.
major, in a wide range of white, cream, green, pink and red shades. Some
are treated as annuals and sometimes sold in bedding plant packs by nurseries.
Woodland
Many umbellifers have pinnate, rather ferny, foliage that
looks delightfully natural in a woodland setting. However, such locations are
often too shaded to allow the plants to flower well. That doesn’t really matter
very much with the likes of the common glossy-leaved angelica (A. pachycarpa)
and bronze-leaved fennel (Foeniculum vulgare ‘Purpurascens’) because
they’re grown more for their foliage than their flowers.
Bupleurum fruticosum, one of the few shrubby
umbellifers, also does well in semi-shaded conditions. Because it’s evergreen,
the glossy green foliage is a year-round feature, and from late summer it
produces conspicuous heads of yellow-green flowers.
Hacquetia epipactis is a charming little woodlander
that with time can carpet a reasonably large area. It dies away entirely over
winter and its first sign of new life in late winter to early spring is when
the bright yellow-green flower bracts emerge. As the flower stems gain height
so the foliage follows.
Cow parsley (Anthriscus sylvestris), along with the similar false bishop’s weed (Ammi majus), is one of several plants often sold under the name Queen Anne’s lace. It blooms in summer and as you’d expect it produces lacy heads of white flowers carried on stems up to 1.5m tall. Cow parsley will grow in sun or shade but will be far more compact in full sun. Its lacy appearance is best appreciated when the plant is grown in a dappled woodland.
Rockery
Some of the smaller umbellifers make ideal rockery plants. The best is undoubtedly Azorella trifurcata, which forms ground-hugging hummocks of lush deep green foliage that in late spring and early summer are studded with small heads of yellow-green flowers. It’s a tough plant that requires little or no attention other than an occasional watering.
The native Aciphylla, Anisotome and Gingidia species also do well in rockeries. However, they have to be well established and they’re not always easy to keep alive when young. Absolutely perfect drainage seems to be the key. Plant them in a 50/50 mix by volume of very fine shingle grit and potting mix and take care to dig a planting hole large enough to allow their taproots to develop freely.
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However, you use them, the umbel family is well worth trying. There are many that are grown in European gardens that simply don’t occur here, at least not commonly, so scouring foreign seed catalogues could be worthwhile if you want something really different.
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Weeds
No summary of the umbellifers would be complete without mentioning that some of them can be rather invasive and that a few are very toxic. Think twice before planting the likes of giant hogweed or black parsley because they can quickly become dominant and are not always easy to eradicate.
Giant hogweed is also toxic: contact with its sap can cause a rash or blisters to develop if the skin is exposed to sunlight. This effect, known as phototoxicity or phytophotodermatitis, is quite common among the umbellifers.
The best-known poisonous umbellifer is of course hemlock (Conium maculatum), which grows wild in many areas. Fortunately there is little about the plant that would encourage anyone to eat it, though children sometimes play with the hollow stems and stock have occasionally been fatally poisoned when hemlock occurring as a pasture weed has been inadvertently baled with hay.
Water hemlock (Cicuta maculata) is an even more toxic plant. It looks rather like a giant parsnip and is native to North America. Fool’s parsley (Aethusa cynapium) is very appropriately named, resembling common parsley but with far less pleasant results when consumed.
Although many of the poisonous umbellifers have long been used in herbal medicines and extracts, do not be tempted to try anything other than those certified as safe.
Cultivation
Large taproots are common among the umbellifers — not surprising, considering the nature of carrot and parsnip roots. For that reason they usually perform best in soils that are loose and deep enough to allow the roots to develop freely. If the roots are impeded the plant may become stunted or top-heavy and prone to blowing over, while poor drainage can cause rotting as well as underdeveloped roots.
Prepare the soil in advance of planting because if there are any problems they will be hard to correct afterwards without damaging the plants. Any sort of root disturbance, especially transplanting, is likely to set the plants back, so keep deep cultivation to a minimum. A light hoeing followed by surface mulching should keep any competing weeds at bay.
Propagation
Some umbellifers, such as bronze-leaved fennel, can be
raised from basal cuttings taken in spring, but the tendency to resent root
disturbance means that most are raised from seed. The seeds are generally tiny
and very freely produced. They often have a rather short viability period and
should be sown as fresh as possible. If you’re buying seed in commercial
packets make sure that is well within its expiry date.
Umbellifers are generally hermaphrodite and a single plant
is capable of producing fertile seed. Naturally though, if you’re looking to
sow seed of a selected form it will need to be one that comes true to type from
seed. Otherwise, consider taking basal cuttings of the new growth in spring.
In most cases the seed germinates quickly and easily and
requires no special treatment. However, it’s important that the young seedlings
are pricked out as soon as they’re large enough to handle, otherwise their
tender roots could be damaged. Never let a tray of seedlings get to the stage
where they have formed a dense mass of roots that are starting to emerge from
the drainage holes.
Pests and diseases
Vigorous is a word that aptly describes most umbelliferous
plants. The few pests and diseases they do suffer from seldom cause anything
more than minor damage. One exception though is carrot rust fly, the larvae of
which burrows through the taproot and is a major pest of carrots and sometimes
parsnips. The flies attack other umbellifers, but they don’t seriously affect
plant growth and they’re seldom noticed because the roots aren’t harvested.
Many control methods have been advocated. Soil insecticides
are probably the most reliable if sprinkled along the seed row at sowing. Delaying
sowing until late November also helps because the adult egg-laying moths become
scarce by then. Other methods may work but they would require some trial and
error testing, particularly with timing. These include disturbing the moths’
method of locating host plants (smell) by mixing coffee grounds with your
carrot seed; diverting the moths from the carrots by planting parsley alongside
the carrot row; and planting carrots in raised beds to keep them above the
moths, which generally fly very close to the ground.
Small caterpillars can often be seen feeding on umbelliferous flower heads. They seldom cause much damage and if they do get out of hand they are easily controlled with pyrethrum sprays or powders.
Aphids often attack the tender young growth of fennel, dill and parsley, as do the spittlebugs (the larvae of leafhoppers). An occasional hosing off or spraying with a mild detergent solution is usually all the control required.
Fungal diseases, such as mildew and rust, most often occur too late in the season to cause severe damage or disfigurement. Rust, either white or orange, on celery is, however, a serious problem and may require the use of fungicides for control.
Copyright Geoff Bryant
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