Native Impatiens Species Research Articles

Comparative floral and pollen morphology of some invasive and native impatiens species

To evaluate the hypothesis of competitive superiority of invasive species, we compared the invasive Impatiens parviflora DC. and I. Glandulifera royle, the naturalized I. Nevskii pobed. and the native I. Noli-tangere L. in the flowers’ morphometric characters at different phases of anthesis. The characters in which alien species have a competitive superiority over closely related I. Noli-tangere are revealed. Morphological variability was studied by morphometric observations of the following characters: bud: length and diameter; spurred sepal: length and width; spur: length and diameter; lateral sepal: length and width; largest petal: length and death; large lobe of lateral petal: length and width; small lobe of lateral petal: length and width; anther: length; stamen’s filament: length; calyptra: length and width; ovary: length and diameter; length of a style, length of a stigma. There is a tendency for alien Impatiens species of the earlier development of androecium and gynoecium: сaliptra is formed at the stage of uncolored bud, the pistil is differentiated in ovary, short style and stigma is formed at the stage of colored bud. No other flowers’ morphometric characters, representing competitive advantage of the invasive I. Glandulifera and I. Parviflora over the native I. Noli-tangere and naturalized I. Nevskii were identified.

Latitudinal variation of life-history traits of an exotic and a native impatiens species in Europe

Understanding the responses of invasive and native populations to environmental change is crucial for reliable predictions of invasions in the face of global change. While comparisons of responses across invasive species with different life histories have been performed before, comparing functional traits of congeneric native and invasive species may help to reveal driving factors associated with invasion. Here we compared morphological functional trait patterns of an invasive species (Impatiens parviflora) with its congeneric native species (I. noli-tangere) along an approximately 1600 km European latitudinal gradient from France (49°34′N) to Norway (63°40′N). Soil nitrogen was recorded during six weeks of the growing season, and light, soil moisture, and nutrient availability were estimated for each sampled population using community weighted means of indicator values for co-occurring species. Temperature data were gathered from nearby weather stations.Both the native and invasive species are taller at higher latitudes and this response is strongest in the invasive species. Seed mass and number of seeds per capsule increase in I. noli-tangere but decrease in I. parviflora towards higher latitudes. Surprisingly, plant height in the invasive I. parviflora decreases with increasing soil nitrogen availability. The latitudinal pattern in seed mass is positively related to temperature in I. noli-tangere and negatively in I. parviflora. Leaf area of both species decreases with increasing Ellenberg indicator values for nitrogen and light but increases with increasing soil moisture. Soil nitrogen concentrations and Ellenberg indicator values for nitrogen have significant positive (I. noli-tangere) and negative (I. parviflora) effects on the number of seeds per capsule. Our results show that the native I. noli-tangere has efficient reproduction at its range edge while the invasive I. parviflora shows a marked decrease in seed size and seed number per capsule. These patterns are unrelated to the growth and obtained size of the plants: even low soil nitrogen availability in the north seemed not to limit plant growth and size. Our results suggest that the invasive I. parviflora tends to become more invasive at lower latitudes by producing heavier seeds and more seeds per capsule.

Juvenile biological traits of Impatiens species are more strongly associated with naturalization in temperate climate than their adult traits

Potentially invasive species can be identified before they start to spread by comparing their traits with those of successful invaders. A powerful tool for delimiting the traits associated with invasiveness are analyses of a number of species of the same genus, where it is more likely to detect relevant differences because of elimination of biases that constrain the search for such traits in whole floras. Since the influence of traits on invasion success may differ with respect to the stage of the plant's life cycle, comparative studies should address the whole life cycle, including early stages. Here we studied which biological traits are associated with the ability to naturalize within the genus Impatiens, how frequency of planting affects naturalization success, and whether naturalized species with biological traits similar to the native representative of this genus are more successful. The genus Impatiens includes a number of cultivated species popular in horticulture, among them several widespread invaders. We used one native and 10 alien annual taxa. This data set involved all commonly cultivated species, and representatives of different invasion status in Europe. In garden experiments and climatic chambers we measured seed mass, time to germination, percentage of seeds germinated, seedling growth rate, total seedling biomass, seedling root/total biomass ratio, adult biomass and fecundity. These traits and planting frequency were used to explain the invasion success of the species, expressed as (i) invasion status in Europe and (ii) the number of global temperate regions in which the species has been reported as naturalized. The frequency of planting was used as a proxy of propagule pressure to separate this potentially biasing factor known to affect plant invasiveness from the effect of plant traits. We found that both species traits and frequency of planting were correlated with naturalization. Species naturalized in many temperate regions of the world had heavier seeds, high seedling growth rate and allocated low proportion of seedling biomass to roots. Importantly, common planting was more strongly correlated with naturalization success than with biological traits. Impatiens species naturalized in Europe exhibited better seed germination in the common garden, and it took a longer time for the seeds to germinate. Species escaped from cultivation but occurring only as casuals in Europe had heavy seeds and invested more resources into shoots than roots, whereas species not escaping from cultivation were characterized by fast seed germination and light seed. In general, traits linked to early stages of the life cycle were more strongly associated with invasion success than those of the adults. Frequently planted species tend to naturalize more easily than those planted scarcely. The successful invaders share traits similar to the one native Impatiens species in Europe and those with traits distinct from it do not invade. Our results indicate that many Impatiens species represent potential invaders should their planting become more widespread; this prediction is supported by the fact that Impatiens species included in the experiment completed their life cycles in an experimental garden in central Europe.

Demonstration of pollinator-mediated competition between two native Impatiens species, Impatiens noli-tangere and I.textori (Balsaminaceae).

Plant–plant interspecific competition via pollinators occurs when the flowering seasons of two or more plant species overlap and the pollinator fauna is shared. Negative sexual interactions between species (reproductive interference) through improper heterospecific pollen transfer have recently been reported between native and invasive species demonstrating pollination-driven competition. We focused on two native Impatiens species (I. noli-tangere and I. textori) found in Japan and examined whether pollinator-mediated plant competition occurs between them. We demonstrate that I. noli-tangere and I. textori share the same pollination niche (i.e., flowering season, pollinator fauna, and position of pollen on the pollinator's body). In addition, heterospecific pollen grains were deposited on most stigmas of both I. noli-tangere and I. textori flowers that were situated within 2 m of flowers of the other species resulting in depressed fruit set. Further, by hand-pollination experiments, we show that when as few as 10% of the pollen grains are heterospecific, fruit set is decreased to less than half in both species. These results show that intensive pollinator-mediated competition occurs between I. noli-tangere and I. textori. This study suggests that intensive pollinator-mediated competition occurs in the wild even when interacting species are both native and not invasive.

Germination dynamics and seedling frost resistance of invasive and native Impatiens species reflect local climatic conditions

Abstract Invasion of some alien plants is considered to be associated with inter-population differentiation and adaptations to local conditions. To obtain an insight into these processes it is convenient to compare invasive plants with their native congeners. The intra-specific differentiation during invasion was studied using four Impatiens (Balsaminaceae) species in Central Europe: native Impatiens noli-tangere and three aliens (highly invasive Impatiens glandulifera , less invasive Impatiens parviflora and potentially invasive Impatiens capensis ). Differentiation in traits important for the establishment (germination; seedling emergence; seedling frost resistance) was measured in a laboratory and an experimental garden using seed collected from five natural populations of each species. Frost resistance of I. capensis , currently invasive in Western Europe, was within the scope of other congeners and it does not seem to be a barrier to spread of the species into Central Europe. Among-population differences were found within all species except I. capensis . In I. noli-tangere , I. glandulifera and I. parviflora the differences were related to the climatic characteristics in early spring at the source localities, which indicates that individuals may be adapted to local conditions. The differences found between the populations of I. noli-tangere , I. glandulifera and I. parviflora are likely to reflect the frost sensitivity of the species. In the highly frost-sensitive I. parviflora differentiation was found both in germination and frost resistance of individual populations. In I. glandulifera the differences among populations in frost sensitivity depended on temperature at the seed source and corresponded to the pattern of emergence of seedlings in the garden. In the native I. noli-tangere , the differences among populations in the time of germination depended on temperature at the seed-source locality. Since local adaptations were indicated both in native and invasive species studied, they are unlikely to provide the invasive Impatiens species with an advantage against the native congener, at least in terms of the traits investigated.

Impatiens noli‐tangere L.

<i>Impatiens noli‐tangere</i> L.