It appears that is was suggested to be listed way back in 1982 along with lots of other plants and animals.
Then in 1992 the PMV and 6 other vetch type plants were specificaly proposed to be listed as endangered. Then finally in 1998 it was
All doc's found here: [url=http://ecos.fws.gov/species_profile/servlet/gov.doi.species_profile.servlets.SpeciesProfile?spcode=Q2ND#status[/url]
Click on Go to Federal Registry Documents
QUOTE
PMV was first was first
described as A. peirscvG’ by Munz and
Jeer. P. McBumey ia 1932. The type was
coilected by Munz and Charles L
Hitchdork* “from sand dunes between
Holtvilie and Yuma” in Imperial County,
sad naned af!er amateur botanist Frank
W. Peirson [iiameby 15541. In 1944,
Barneby recognized A. peirscnii as a
junior synonym of a A. njveus, but then
later described both as varieties of
Astragalus magdalenae after studying
additional collections (Bameby 1358).
Feirson’s milk-vetch is a stout, shortlived
perennial reaching z to 7 dm (7.9 to
27 in) high; sie;;ls and leaves are
ccvered with fine siiky hairs; leaves are
5 to 15 cm (2.0 to 5.9 in) long, with 8 to 12
sma!l oblong leaflets. The flowers are
dull purple, arranged in 10 to 17-
flowered racemes; the pods are 2 to 3.5
cm (0.8 to 1.4 in) long, inflated, with a
triangular beak. The variety peirsonii is
separated from two other varieties of
Astragalus magdalenae on the basis of
the number of leaflets, the length of the
peduncles, and the diameter of the pods.
With a length of 4.5 to 5.5 mm (less than
0.2 in], Peirson’s milk-vetch has the
largest seeds of any Astmgalus in North
America (Bameby 1~641.
Peirson’s milk-vetch occurs on slopes
and hollows of windblown dunes in the
Sonoran Desert. Of the taxa included in
this proposal, Astmgolus magdalenae
var. peirsonii potentially has one of the
widest distributions, which, according to
Shreve and Wiggins (1964) and Munz
(1974) ranges from Borrego Valley in
eastern San Diego County to Yuma on
the California-Arizona border, and south
into northeastern Baja California. The
plant, however, has not been seen in
Borrego Valley since 1959; surveys in
1978 failed to detect it there (Spolsky
1978). Another historic location, west of
the Salton Sea, cannot be confumed.
Peirson’s milk-vetch is currently known
to occur aIong the north and west flanks
of the Algodones Dunes extending into
northeastern Baja California. The
Algodonea Dunes are primarily on
Federal lands managed by the Bureau.
The primary threat to Peirson’s milkvetch
is the alteration of habitat from
off-road vehicle activity. The plant is
also threatened with stochastic
extinction due to the limited size of its
popula!ions. Surveys for the plant on the
Algodones Dunes were done in IQ78 and
1990. While the techniques used in the
two surveys do not permit direct
comparison, they indicate a downward
trend in population size (Westec 1977,
Ecos 1990).
described as A. peirscvG’ by Munz and
Jeer. P. McBumey ia 1932. The type was
coilected by Munz and Charles L
Hitchdork* “from sand dunes between
Holtvilie and Yuma” in Imperial County,
sad naned af!er amateur botanist Frank
W. Peirson [iiameby 15541. In 1944,
Barneby recognized A. peirscnii as a
junior synonym of a A. njveus, but then
later described both as varieties of
Astragalus magdalenae after studying
additional collections (Bameby 1358).
Feirson’s milk-vetch is a stout, shortlived
perennial reaching z to 7 dm (7.9 to
27 in) high; sie;;ls and leaves are
ccvered with fine siiky hairs; leaves are
5 to 15 cm (2.0 to 5.9 in) long, with 8 to 12
sma!l oblong leaflets. The flowers are
dull purple, arranged in 10 to 17-
flowered racemes; the pods are 2 to 3.5
cm (0.8 to 1.4 in) long, inflated, with a
triangular beak. The variety peirsonii is
separated from two other varieties of
Astragalus magdalenae on the basis of
the number of leaflets, the length of the
peduncles, and the diameter of the pods.
With a length of 4.5 to 5.5 mm (less than
0.2 in], Peirson’s milk-vetch has the
largest seeds of any Astmgalus in North
America (Bameby 1~641.
Peirson’s milk-vetch occurs on slopes
and hollows of windblown dunes in the
Sonoran Desert. Of the taxa included in
this proposal, Astmgolus magdalenae
var. peirsonii potentially has one of the
widest distributions, which, according to
Shreve and Wiggins (1964) and Munz
(1974) ranges from Borrego Valley in
eastern San Diego County to Yuma on
the California-Arizona border, and south
into northeastern Baja California. The
plant, however, has not been seen in
Borrego Valley since 1959; surveys in
1978 failed to detect it there (Spolsky
1978). Another historic location, west of
the Salton Sea, cannot be confumed.
Peirson’s milk-vetch is currently known
to occur aIong the north and west flanks
of the Algodones Dunes extending into
northeastern Baja California. The
Algodonea Dunes are primarily on
Federal lands managed by the Bureau.
The primary threat to Peirson’s milkvetch
is the alteration of habitat from
off-road vehicle activity. The plant is
also threatened with stochastic
extinction due to the limited size of its
popula!ions. Surveys for the plant on the
Algodones Dunes were done in IQ78 and
1990. While the techniques used in the
two surveys do not permit direct
comparison, they indicate a downward
trend in population size (Westec 1977,
Ecos 1990).
Edited for link error.