Delphinium is a genus of about 300 species of perennial flowering plants in the family
Ranunculaceae, native throughout the Northern Hemisphere and also on the high mountains
of tropical Africa. All members of the Delphinium genus are toxic to humans and livestock. The
common name "larkspur" is shared between perennial Delphinium species and annual species of the
genus Consolida. Molecular data show that Consolida, as well as another segregate genus,
Aconitella, are both embedded in Delphinium. The name "delphinium" derives from the Latin
for "dolphin", referring to the shape of the nectary.
Description
The leaves are deeply lobed with three to seven toothed, pointed lobes in a palmate
shape. The main flowering stem is erect, and varies greatly in size between the species,
from 10 centimetres in some alpine species, up to 2 m tall in the larger meadowland species.
In June and July, the plant is topped with a raceme of many flowers, varying in color
from purple and blue, to red, yellow, or white. In most species each flower consists of five
petal-like sepals which grow together to form a hollow pocket with a spur at the end, which
gives the plant its name, usually more or less dark blue. Within the sepals are four
true petals, small, inconspicuous, and commonly colored similarly to the sepals. The eponymous
long spur of the upper sepal encloses the nectar-containing spurs of the two upper petals.
The seeds are small and often shiny black. The plants flower from late spring to late
summer, and are pollinated by butterflies and bumble bees. Despite the toxicity, Delphinium
species are used as food plants by the larvae of some Lepidoptera species, including the
dot moth and small angle shades. Taxonomy
Delineation of Delphinium
Genetic analysis suggests that Delphinium sensu lato, as it was delineated before the
21st century, is polyphyletic. Nested within Delphinium s.l. are Aconitella, Consolida,
and Aconitum. To make Delphinium monophyletic, several interventions were made. The new genus
Staphisagria was erected containing Delphinium staphisagria, D. requini, and D. pictum, representing
the sister group to all other Delphinieae. Further genetic analysis has shown that the
two large subgenera Aconitum and Aconitum are the sister group to Aconitum gymnandrum,
Delphinium, Delphinium, Consolida and Aconitella. To make Aconitum monophyletic, A. gymnandrum
has now been reassigned to a new monotypic genus, Gymnaconitum. Finally, Consolida and
Aconitella are synonymized with Delphinium. Subgenera
D. arthriscifolium is sister to all other species of Delphinium sensu stricto. It should
be placed in its own subgenus, but no proposal naming this subgenus has been made yet. The
subgenera Delphinium and Delphinium are sister to the group consisting of the species of
Consolida and Aconitella, which together make up the subgenus Delphinium. Aconitella cannot
be retained as a subgenus because A. barbata does not cluster with the remaining species
previously assigned to that genus, without creating five further subgenera.
Species
Selected species include: Delphinium arthriscifolium
Delphinium brunonianum Delphinium cardinale
Delphinium cheilanthum Delphinium consolida
Delphinium elatum Delphinium formosum
Delphinium grandiflorum Delphinium nuttallianum
Reassigned species Several species of Delphinium have been reassigned:
D. pictum = Staphisagria picta D. requienii = Staphisagria requienii
D. staphisagria = Staphisagria staphisagria Ecology
Delphiniums can attract butterflies and other pollinators.
Cultivation Various delphiniums are cultivated as ornamental
plants, for traditional and native plant gardens. The numerous hybrids and cultivars are primarily
used as garden plants, providing height at the back of the summer border, in association
with roses, lilies, and geraniums. Most delphinium hybrids and cultivars are
derived from D. elatum. Hybridisation was developed in the 19th-century, lead by Victor
Lemoine in France. Other hybrid crosses have included D. bruninianum, D. cardinale, D.
cheilanthum, and D. formosum. Numerous cultivars have been selected as garden
plants, and for cut flowers and floristry. They are available in shades of white, pink,
purple, and blue. The blooming plant is also used in displays and specialist competitions
at flower and garden shows, such as the Chelsea Flower Show.
The 'Pacific Giant' hybrids are a group with individual single-color cultivar names, developed
by Reinelt in the United States. They typically grow to 4–6 ft tall on long stems, by 2–3 ft
wide. They reportedly can tolerate deer. Millennium delphinium hybrids, bred by Dowdeswell's in
New Zealand, are reportedly better in warmer climates than the Pacific hybrids. Flower
colors in shades of red, orange, and pink have been hybridized from D. cardinale by
Americans Reinelt and Samuelson. The following delphinium cultivars have received
the Award of Garden Merit from the British Royal Horticultural Society:
Toxicity All parts of these plants are considered toxic
to humans, especially the younger parts, causing severe digestive discomfort if ingested, and
skin irritation. Larkspur, especially tall larkspur, is a significant cause of cattle
poisoning on rangelands in the western United States. Larkspur is more common in high-elevation
areas, and many ranchers delay moving cattle onto such ranges until late summer when the
toxicity of the plants is reduced. Death is through cardiotoxic and neuromuscular blocking
effects, and can occur within a few hours of ingestion. All parts of the plant contain
various diterpenoid alkaloids, typified by methyllycaconitine, so are very poisonous.
Uses
The juice of the flowers, particularly D. consolida, mixed with alum, gives a blue ink.
References
External links GRIN: Species in the genus Delphinium' — with
links by species for information + synonyms. USDA-ARS: Larkspur—Delphinium spp. Fact
Sheet — native U.S. species and grazing toxicity.
MBG—Kemper Center for Home Gardening: Delphinium "Pacific Giant Hybrids" — horticultural
information. Dowdeswell's Ltd: "Growing New Millennium
Delphiniums in the U.S. & Canada" — horticultural information.