Thursday, 9 June 2016

30 Days Wild | Day 8 - The Pea family

Today for 30 Days Wild I had a go at another of my Identiplant assignments, about Fabaceae - the Pea family. I'm fairly familiar with this family as many of its members grow near my office so I thought I should be able to get through it fairly quickly. For the first part of the assignment I had to find three of the four species Medicago lupulina (Black Medick), Trifolium dubium (Lesser Trefoil), Lathyrus pratensis (Meadow Vetchling) and Lotus corniculatus (Bird's-foot Trefoil), and describe their diagnostic features. I think these can all be found near my workplace but I haven't spotted any Meadow Vetchling this year, I don't think it is in flower yet - so I found the other three. For the second part of the assignment I had to find either Vicia sepium (Bush Vetch) or Vicia cracca (Tufted Vetch) and key it out using the Wild Flower Key; I found Vicia cracca.

Diagnostic features of the pea family (generally):
  • Usually compound pinnate or trifoliate leaves.
  • Unique flower structure: 5 sepals fused into tube, 5 free petals – upper standard, 2 wings on either side enclosing keel formed from 2 lower inner petals. 10 stamens within keel – lower 2/3 of all or sometimes all but one fused into tube surrounding carpel. 
Diagnostic features of Medicago lupulina:

  • Leaves have mucronate tips and are downy.
  • Flowers/fruit-heads stay upright once flowering has finished.
Black Medick (Medicago lupulina).
Diagnostic features of Trifolium dubium:
  • Leaves have no mucronate tips are are mostly hairless.
  • Flowers/fruit-heads droop down once flowering has finished.
Lesser Trefoil (Trifolium dubium).
As the previous two species are so similar, the diagnostic features are those which are crucial in telling the two apart. The difference between the flowers/fruit heads wasn't one that was particularly highlighted in the Wild Flower Key but it's one that I noticed in real life - we'll see what my tutor thinks of it. There are other diagnostic characteristics too, to do with fruit structure, but for these assignments I am only supposed to highlight features that I have actually observed - and I didn't find any ripe fruits yet!

Diagnostic features of Lotus corniculatus:
  • Yellow flowers with orange/red tinge – red buds.
  • Trifoliate leaves but with extra leaf pair at base of stalk.
  • Hairless oval leaves.
  • Solid stems.
  • Sepal points are erect, not reflexed as in L. pedunculatus (another very similar species).
Bird's-foot Trefoil (Lotus corniculatus).
I managed to successfully key out Vicia cracca using the Wild Flower Key. I won't post the whole sequence here, here's a pic of the start of the pea family key though - I am getting better at using these having never really got to grips with keys before this course, you can see why it's so important to be familiar with the terminology!

Start of the pea key!
Tufted Vetch (Vicia cracca).
Then just for fun I also found two more pea family members!

Grass Vetchling (Lathyrus nissolia).
Hop Trefoil (Trifolium campestre).

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