FIELD COW-WHEAT

Melampyrum arvense

Broomrape Family [Orobanchaceae]

month8jun month8june month8jul month8july month8aug month8sep month8sept

status
statusZneophyte
 
flower
flower8bicolour
 
flower
flower8mauve
 
inner
inner8yellow
 
morph
morph8zygo
 
petals
petalsZ2
 
type
typeZspiked
 
stem
stem8square
 
toxicity
toxicityZmedium
seeds
rarity
rarityZrare
 

25th June 2004. Photo: (CC by 2.0) Colin Pope
Grows to 50cm high in cornfields and grassy margins, also in hedgerows.


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
Stems may branch, as does the nearest near the bottom of the photo.


Alto Piano Plateux, Abruzzo, Italy Photo: © Dylan Warren-Davis
The plateux here has never been subject to agriculture and is under snow for 6 months of the year, seemingly just right for these Cow-wheats which are here with many other species that are rare in the UK.


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
Leaves lanceolate, long and narrow, with long teeth, in pairs in quadrature along the square stem.


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
Flowers in a short spike, mauve coloured, often with the lower lip yellow (or white).


30th June 2006, St. Lawrence, IoW. Photo: (CC by 2.0) Geoff Toone
On the underside, the lower lip has two elongated pits.


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
Flowers mingle amidst spear-shaped bracts and long wire-shaped sepal teeth, all mauve coloured.


4th Aug 2007, St Lawrence, IoW Photo: (CC by 2.0) Mike Cotterill
Before opening the flowers resemble those of Yellow-Rattle with their bird-like appearance.


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
These are not petals but rather concolorous long and spear-head shaped bracts. The concolorous fine threads are greatly elongated sepal teeth.


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
The mauve bracts are also slightly frayed at the edges.


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
The flowers themselves are mauve, some having a yellow/white band on the underside. Un-opened they have very distinctive folds - three-winged with a rib on the underside.


30th June 2006, St. Lawrence, IoW Photo: (CC by 2.0) Geoff Toone
Two elongated pits, best seen in flower upper right, or the one below and to the left of that one.


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
The flowers also have a very long but bent tubular part as they emerge from the greenish-white sepal. Perhaps un-opened flowers look like a Guppie fish or some kind of whale with a trimeran or speed-boat type keel. Note too the walrus-type moustache. The pinkish-white sepal tubes (dead centre) can be seen clearly in this photo with their wire-like extremely long and thin mauve-coloured sepal teeth.


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
The flowers have a closed throat but one which bees can force open wider to pollinate them. They have a Canary-bird look about them with a prominent head and slight beak, characteristic of other Cow-wheats such as Common Cow-wheat (Melampyrum pratense) and slightly similar to flowers of Yellow Rattle (Rhianthus minor). There is a curled-back lower lip and just above that a short-haired 'moustache' (pink here).


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
The stem has short white hairs and is square. Lower leaves are long and narrow but with long teeth-like auricles as they adjoin the stem.


1st July 2013, Portsdown Hill, Hampshire. Photo: © Dawn Nelson
Leaves conjoined in opposite pairs, some forming a boat around the square stem, much the same as that which Teasel does. In the case of Teasel it is suspected that the compounds produced by dead decaying insects who get drowned in any pool of rain-water gathering in the hollow are made use of by the plant. The same may be true for Field Cow-wheat(?). The undersides of these bracts have minute glands which produce nectar to attract insects such as ants, bumblebees and other insects, so it may not be a far-off guess. So, your Author surmises: is it possible that not only is it parasitic on the roots of other plants but might also be hemi-parasitic on insects(?).

After all, it is thought that the similar (but larger) 'boats' around the stems of Teasel, which also accumulate rain-water, also derive some nutrients from the dead and dying insects which drown in the pools.

Long teeth on leaves form 'row-locks' on the 'boat'. The leaves alternating at right-angles to each other along the stem.



4th Aug 2007, St Lawrence, IoW Photo: (CC by 2.0) Mike Cotterill
A close-up of one of the deeply divided bracts/leaves on the stem.


Not to be semantically confused with : Cowbane (Cicuta virosa) nor with Cowslip (Primula veris) nor Cowberry (Vaccinium vitis-ideae) [plants with similar name belonging to differing Families]

Uniquely identifiable characteristics

Distinguishing Feature : See captions.

Cow-wheats are  hemi-parasitic, obtaining nutrients from the roots of other plants when they can but are capable of surviving without being parasitic on a host plant. Hence hemi-parasitic. It grows on many differing hosts but grows very well on Lucerne, (Medicago sativa ssp. sativa) a plant belonging to the Pea Family (Fabaceae) presumably because that can fix nitrogen from the air.

As showy as Large-Flowered Hemp-Nettle (Galeopsis speciosa) but that has yellow-purple flowers and is in the Dead-nettle Family (Lamiaceae). Both grow in arable fields, but the Hemp-nettle prefers a peaty soil whereas Field Cow-wheat prefers Cornfields, hedge-banks and grassy field margins.

It is a very rare and protected plant growing in the South East of England. Its range is decreasing fast due to ever intensive agricultural farming practices.

The seeds are poisonous, containing Aucubin an iridoid glycoside.

In many Melampurum species the flowers change colour from yellow to red in older flowers - it is thought after they have been pollinated. This serves as an indicator to the pollinating insect that it is wasting its time and energy visiting this floret which no longer contains nectar sustenance.


  Melampyrum arvense  ⇐ Global Aspect ⇒ Orobanchaceae  

Distribution
 family8Broomrape family8Orobanchaceae

 BSBI maps
genus8Melampyrum
Melampyrum
(Cow-Wheats)

FIELD COW-WHEAT

Melampyrum arvense

Broomrape Family [Orobanchaceae]