Introduction:
The New Mexico bird's-foot trefoil, also called pine deervetch is a perennial herb of the pea family Fabaceae. This plant is recorded to grow, “where nothing else grows” (database of the Lady Bird Johnson Wildflower Center, 2010). At EPCC we have collected the seeds of this plant for the Lady Bird Johnson Wildflower Center in Austin that organized the Millennium Seed Collection Project for Texas. Since not much else than the original plant description and a few records of plant findings are reported in the literature, we took this opportunity to study the role of this plant in its environment.
The role of the New Mexico bird's-foot trefoil (Lotus plebeius) in the local
ecosystem
Dr. Gertrud Konings, Michael Eason, and David Quintanar
Introduction:
The New Mexico bird's-foot trefoil, also called pine deervetch is a
perennial herb of the pea family Fabaceae. This plant is recorded to
grow, “where nothing else grows” (database of the Lady Bird Johnson
Wildflower Center, 2010). At EPCC we have collected the seeds of this
plant for the Lady Bird Johnson Wildflower Center in Austin that
organized the Millennium Seed Collection Project for Texas. Since not
much else than the original plant description and a few records of plant
findings are reported in the literature, we took this opportunity to study
the role of this plant in its environment.
Results: The green caterpillar is shown next to the seed pod of
the plant. On the SEM photos the head structures, setae, the
thoracic legs and abdominal prologs can be seen. The
caterpillar developed into the butterfly Plebejus melissa, the
Melissa Blue. The empty shell of the pupa is visible on the left
insert.
Methods:
While collecting herbarium specimens and seeds, we found a caterpillar feeding on the plant
and parasitic wasps developing inside the seed pod. A caterpillar was kept in an aerated glass jar
with some leaves and seed pods, to observe its development. It soon entered the pupal stage
and a butterfly emerged. A caterpillar and the developing stages of the wasp were
photographed through a light microscope and then placed into some alcohol to observe it with
the Scanning Electron Microscope (SEM). Since the plant belongs to the Fabaceae, we also
examined it for root nodules using the SEM and the light microscope. After fragmenting the
nodules with a scalpel to prepare smears and staining them with Methylene Blue and Crystal
Violet, the symbiotic bacteria in the nodule were photographed.
Results: The developmental stages of the wasp parasite inside the seed
pod are documented. The red eye becomes clearly visible. Mature wasps
escape from the pod by eating a hole through the dry pod. The wasp was
identified as a Braconid Wasp.
Root nodules are tiny and best identified with the light
microscope. A SEM picture reveals its appearance. The
smear reveals bacteria within the cells of the nodule.
Plebejus melissa –
pupa / caterpillar
Root Nodules with symbiotic
Bradyrhizobium bacteria
Braconid Wasp
developing in seed
pods