Ecology and management of an exotic weed Phalaris minor - Invasive Plants: Ecological and Agricultural Aspects - page 160

Table 1. Terminology for alien plants
Terminology, synonyms (in parenthesis), definition, and interpretation
Native plants (indigenous plant)
Taxa that have originated in a given area without intentional or unintentional involvement of
humans. P. minor is not a native plant of India, because it was introduced from Mexico.
Alien plant (exotic plant, introduced plant, non-indigenous plant/species (NIS), non-native plant)
Taxa that are not native to the area and whose presence in the area is due to intentional or
unintentional human involvement. P. minor is an exotic or alien plant of India because it is not
native and is present in cultivated fields, particularly wheat.
Naturalized plant (established plant)
Alien plant that sustain self-replacing populations for at least ten years without direct
intervention of humans by recruitment from seed or ramets capable of independent growth. P.
minor is not a naturalized species, because it is successful in cultivated fields but rarely
observed in abandoned fields. Long-term studies are needed to determine the survival rate and
growth of P. minor in wheat fields abandoned for at least ten years.
Invasive plant (invader)
Invasive plants are a subset of naturalized plants that reproduce in large number at considerable
distance from the parent plant, and thus have the potential to spread over a large area. Currently
we do not have evidence that P. minor is an invader, because P. minor has restricted itself to
cultivated fields and its presence in northwestern India is due to wheat seed contamination.
Terminology for P. minor
Based on field observations and empirical evidence of the ecology, P. minor can be best
identified as an alien (exotic or non-indigenous) weed in India, because: i) it is a non-native
plant; ii) it is not escaping its boundaries and is largely restricted to cultivated fields; and iii) it
is growing where it is not desired, causing considerable crop damage (particularly wheat), and
therefore has significant economic and environmental (due to extensive herbicide use to control
P. minor ) impact.
Modified after [14]. Reproduced with permission from Editors, Taxon
We are not aware of any study showing the potential of P. minor to persist
in cultivated fields abandoned for several (>10) years. P. minor maintains self-
replacing populations through seeds in cultivated fields with human involve-
ment. During wheat harvest, P. minor seeds are incorporated into the soil,
which serves as a seed bank for subsequent years. Agricultural practices, such
as tillage, irrigation and fertilization, seem necessary for P. minor to establish
and grow successively each year. Therefore, P. minor is not a naturalized spe-
cies in India.
At present we do not have sufficient empirical evidence to identify P. minor
as an invasive weed. P. minor has the following characteristics: i) new to the
region, i.e., non-native, ii) not desirable in cultivated fields, iii) causes signifi-
cant economic losses in wheat production, and iv) herbicide use for its control
causes environmental concerns. Based on the above characteristics, P. minor is
recognized as an exotic weed and should not be identified as a naturalized
plant (Tab. 1).