|
|
Leaf |
|
Jimmy Fern
(Notholaena sinuata var. cochisensis)
|
Description
Jimmy fern is an evergreen, erect, fern with
simple, pinnate leaves. The numerous leaflets are scaly
beneath and smooth above. Leaves originate from a short,
chaffy, woody stem. This plant is of the "resurrection"
type, in that the leaflets roll up and become quite dry
when moisture is lacking. They unroll and appear green
and fresh following rain.
Distribution and Habitat
Jimmy fern grows on rocky slopes and crevices and
is often closely associated with some of the grasses characteristic
of dry habitats. It is common in the Trans-Pecos and also
occurs in the Plains and Edwards Plateau regions of Texas.
It extends into New Mexico, Arizona, and south to Mexico.
Regions: 7, 8,
9, 10.
Toxic Agent
The actual toxic agent contained in jimmy fern
is not known. The poison is excreted in milk and not destroyed
by drying of the plant. Jimmy fern poisoning occurs in sheep,
goats and cattle. A trembling reaction called "jimmies"
develops about 48 hours after the animals are fed as much
as 0.5% of their body weight of the fern and are exercised.
It generally takes from 10 to 60 minutes of walking for
animals to develop symptoms. The danger of jimmy fern poisoning
is greatest in wet years from mid-November through February
when other forage is dry and the evergreen fern remains
succulent and relatively palatable
|
Livestock Symptoms
Poisoned animals lag behind the herd, walk with
stilted, uncoordinated motions and finally come to a stop
with arched back. They then tremble violently (the "jimmies"),
respiration and heartbeat increase and they become prostrated.
Further exercise may bring on a fatal attack. Characteristically,
in the last attack the animal takes 3 or 4 stilted steps,
drops, gasps a few breaths and dies almost immediately of
respiratory paralysis.
Integrated Management Strategies
No medicinal treatment is known. Sheep and goats
usually die following ingestion of lethal dose of jimmy
fern. Cattle tremble but usually live. Non-fatal cases
require 5 to 19 days to recover. Most fatalities occur
in the winter thus sufficient forage or supplemental feed
should be supplied to animals in an infested pasture during
this period. Under severe conditions animals should be
moved from pastures in which jimmy fern is abundant during
the winter months before additional losses occur. Under
range conditions it is important to leave sheep strictly
alone during the danger period, since any excitement or
exercise aggravate their condition. Ample watering places
should be provided in pastures where jimmy fern grows
so that animals can water conveniently. Due to the habitat
that jimmy fern typically grows in, herbicidal control
with spot applications is difficult and generally not
justified.
Printable
Version (PDF) 
  
|
