HORSESHOE VETCH

Hippocrepis comosa

Pea Family [Fabaceae]

month8may month8jun month8june month8jul month8july

status
statusZnative
flower
flower8yellow
inner
inner8red
morph
morph8zygo
petals
petalsZ5
stem
stem8round

13th June 2009, Tennyson Down, Totland, IoW Photo: (CC by 2.0) Mike Cotterill
A pallete of Horseshoe Vetch, which grows only on short chalk and limestone turfs.


22nd June 2009, Military Rd, Freshwater. Photo: (CC by 2.0) Mike Cotterill
Here clinging to calcareous cliff sides.


1st Oct 2007, Afton Cliff, IoW. Photo: (CC by 2.0) Mike Cotterill
Forms carpets.


120th June 2009, IoW Photo: (CC by 2.0) Geoff Toone
Stems procumbent to half-erect to 30cm long (exceptionally 50cm).


23rd May 2008, Ashley Down Quarry. Photo: (CC by 2.0) Geoff Toone
Superficial resemblance to Bird's-foot-Trefoil, but the leaves are pinnate with 7 to 25 leaflets (rather than trefoil with just 5 leaflets).


10th June 2009, IoW. Photo: (CC by 2.0) Geoff Toone
Flowers yellow with red stripes (as yet un-opened flower buds may have red tips - far left) in a flat rosette display.


13th June 2009, Tennyson Down, Totland, IoW Photo: (CC by 2.0) Geoff Toone
There are between 4 and 8 flowers (with extremes down to just 2 and up to 12) in a 'flat 'rosette'.


23rd May 2008, Ashey Down Quarry, Ryde, IoW. Photo: (CC by 2.0) Geoff Toone
The sepal tube becomes narrower before the 5 sepal teeth splay slightly outwards.


2nd June 2006, Warton Crag, Lancs. Photo: © RWD
Flowers with 5 petals, typical pea-type in shape, deep-yellow with narrow reddish stripes on the banner. Flowers 5-10mm (up to 14mm). Fruits (not shown yet) are 10-30mm long, very flat, often twisted into twirls, with 3-6 horse-shoe-shaped segments (hence the common name).


10th June 2009, IoW. Photo: (CC by 2.0) Geoff Toone
Leaves are pinnate, with between 7 and 25 leaflets, each leaflet being between 4-8mm long (with extremes of 2mm and 16mm) and oblong to ovate in shape.


23rd May 2008, Ashey Down Quarry, Ryde, IoW Photo: (CC by 2.0) Geoff Toone
Each leaf has paired leaflets and a single one at the end.


Some similarities to : Bird's-foot-Trefoil (Lotus corniculatus) but that has only 5 leaflets in a leaf.

No relation to : Horsetails (species of Equisetum) [a non-flowering plant with similar name].

It is a perennial which is native, occurring only locally in Britain as far north as Westmorland, and in Jersey. It only grows on chalky short grassland, cliffs and clifftops, with a greater concentration in the South. There is none within ~70 miles of Manchester, which is why your Author does not often see it.

3-NITROPROPIONIC ACID (3-NPA)


The plant contains both the toxic 3-NitroPropionic Acid (aka 3-NPA or β-NitroPropionic Acid) as well as the enzyme 3-NPA Oxidase (which is found in the leaves). This enzyme is a very large FlavoProtein (with a mass of 36 kiloDaltons). This enzyme oxidises the 3-NPA to Malonate SemiAldehyde (aka 3-OxoPropionic Acid).

The 3-NPA which the plant contains is also produced in a number of fungi and is a mycotoxin and potent Mitochondrial inhibitor; 3-NPA is thus toxic to humans.

But your Author cannot find out how the 3-NPA gets into the Horseshoe Vetch - is it synthesized by a fungus within Horseshoe Vetch, or does Horseshoe Vetch synthesise its own 3-NPA? Nor can he find out which wins out, does the 3-NPA and the enzyme which destroys it co-exist within Horseshoe Vetch, or does one or other win out? Who knows. Maybe it is better not to eat Horseshoe Vetch, but then again, your Author wouldn't anyway!


  Hippocrepis comosa  ⇐ Global Aspect ⇒ Fabaceae  

Distribution
 family8Pea family8Fabaceae

 BSBI maps
genus8Hippocrepis
Hippocrepis
(Hoseshoe Vetches)

HORSESHOE VETCH

Hippocrepis comosa

Pea Family [Fabaceae]