smooth pigweed and nitrate poisoning

9.22: web.apt`garden/smooth pigweed:

. what intuition should call "(the pollen towers)
-- Amaranthus -- is not easy to name,
due to the confusion over many varieties:
Green Pigweed Amaranthus hybridis
. a native of tropical America .
. those sites have differing pict's? ..
. here one shows my kind is smooth pigweed:
"(The first leaves of redroot and smooth pigweed
are rounded, whereas those of green pigweed
are tapered and slightly pinched toward the end. (Figure 1)
The upper stem of green pigweed is often less hairy
than that of redroot or smooth pigweed.
Redroot pigweed
has a relatively short, thick, compact inflorescence,
with the uppermost central spike
extending only a short distance above the
first branches of the panicle. (Figure 2a)
Green pigweed
has a longer and narrower terminal spike
with fewer but longer branches. (Figure 2b)
Smooth pigweed
has a very narrow, often lax, terminal spike
with numerous short lateral branches. (Figure 2c)

Figure 2c. Mature inflorescences of smooth pigweed.
(this is the kind around here)
. pigweed species occasionally accumulate nitrates
in the stem and branches in concentrations high enough
to poison livestock. [commonly eaten by humans too]
Infestations in silage corn
have been reported to cause
severe illness or death in cattle .).
[. vaguely recall from a china cancer study,
that the occasion for nitrates was a mineral deficiency:
"(Plants require molybdenum to synthesize nitrate reductase,
a molybdoenzyme necessary for converting nitrates
from the soil to amino acids.
When soil molybdenum content is low,
plant conversion of nitrates to nitrosamines increases,
resulting in increased nitrosamine exposure
for those who consume the plants.
Adding molybdenum to the soil in the form of ammonium molybdenate
may help decrease the risk of gastroesophageal cancer
by limiting nitrosamine exposure.).]