Cardamine flexuosa (wavy bittercress).

Cardamine flexuosa is a fast-growing herb that often behaves as a weed in both disturbed and undisturbed sites. It is native to Europe and found throughout much of Asia, and has naturalized in North and South America, South Africa and Australia. This species flowers vigorously and forms dense understorey root mats that alter successional processes and displace native plant species. C. flexuosa is a common agricultural weed in paddy fields, crop gardens and orchards and a common weed of gardens, greenhouses and lawns. It is listed as invasive in Myanmar, the Philippines, Hawaii, Cook Islands, South Georgia and the Sandwich Islands and the Bahamas.

Cardamine flexuosa (wavy bittercress).

Cardamine flexuosa is a fast-growing herb that often behaves as a weed in both disturbed and undisturbed sites. It is native to Europe and found throughout much of Asia, and has naturalized in North and South America, South Africa and Australia. This species flowers vigorously and forms dense understorey root mats that alter successional processes and displace native plant species. C. flexuosa is a common agricultural weed in paddy fields, crop gardens and orchards and a common weed of gardens, greenhouses and lawns. It is listed as invasive in Myanmar, the Philippines, Hawaii, Cook Islands, South Georgia and the Sandwich Islands and the Bahamas.

Trait-dependent resemblance of the flowering phenology and floral morphology of the allopolyploid Cardamine flexuosa to those of the parental diploids in natural habitats

Allopolyploids possess complete sets of genomes derived from different parental species and exhibit a range of variation in various traits. Reproductive traits may play a key role in the reproductive isolation between allopolyploids and their parental species, thus affecting the thriving of allopolyploids. However, empirical data, especially in natural habitats, comparing reproductive trait variation between allopolyploids and their parental species remain rare. Here, we documented the flowering phenology and floral morphology of the allopolyploid wild plant Cardamine flexuosa and its diploid parents C. amara and C. hirsuta in their native range in Switzerland. The flowering of C. flexuosa started at an intermediate time compared with those of the parents and the flowering period of C. flexuosa overlapped with those of the parents. Cardamine flexuosa resembled C. hirsuta in the size of flowers and petals and the length/width ratio of petals, while it resembled C. amara in the length/width ratio of flowers. These results provide empirical evidence of the trait-dependent variation of allopolyploid phenotypes in natural habitats at the local scale. They also suggest that the variation in some reproductive traits in C. flexuosa is associated with self-fertilization. Therefore, it is helpful to consider the mating system in furthering the understanding of the processes that may have shaped trait variation in polyploids in nature.

Angiospermic flora of Gafargaon upazila of Mymensingh district focusing on medicinally important species

Gafargaon upazila has been floristically explored to identify and assess the angiospermic flora that resulted in occurrence of 203 taxa under 174 genera and 75 families. Magnoliopsida is represented by 167 taxa under 140 genera and 62 families, while Liliopsida is constituted by 36 taxa belonging to 34 genera and 13 families. Vegetation analysis shows that herbs are represented by 106 taxa, shrubs 35, trees 54, and climbers by 8 species. In Magnoliopsida, Solanaceae is the largest family possessing 10 species, whereas in Liliopsida, Poaceae is the largest family with 12 species. The study has identified 45 medicinal plants which are used for treatment of over 40 diseases including diabetes, ulcer, diarrhoea, dysentery, fever, cold and cough, menstrual problems, blood pressure and urinary disorders by the local people. Some noticeable medicinal plants used in primary healthcare are Abroma augusta (L.) L.f., Coccinia grandis (L.) Voigt., Commelina benghalensis L., Cynodon dactylon (L.) Pers., Holarrhena antidysenterica Flem., Glycosmis pentaphylla (Retz.) A. DC., Mikania cordata (Burm. f.) Robinson, Ocimum tenuiflorum L. and Rauvolfia serpentina (L.) Benth. A few number of species are also employed in cultural festivals in the study area. Cardamine flexuosa With., Oxystelma secamone (L.) Karst., Phaulopsis imbricata (Forssk.) Sweet, Piper sylvaticum Roxb., Stephania japonica (Thunb.) Miers and Trema orientalis L. have been found to be rare in the investigated area. In order to preserve botanical resources of Gafargaon upazila, particularly the rare, threatened and medicinal plants, conservation measures need to be undertaken through both in-situ and ex-situ methods for their sustainable use.

Efficacy of preemergence herbicides over time

Preemergence herbicides are applied to container-grown nursery crops repeatedly throughout the year, often in 8 to 10 week intervals. Preemergence herbicide efficacy may decline over time, resulting in reduced weed control several weeks after application if weed seed density remains high. The objective of this research is to evaluate efficacy of preemergence herbicides on creeping woodsorrel (Oxalis corniculata L.) and flexuous bittercress (Cardamine flexuosa With.) by applying weed seed from 0 to 10 weeks after herbicide application. Granular formulations of pendimethalin, prodiamine + isoxaben, oxyfluorfen + pendimethalin, and flumioxazin were applied at their maximum labeled rates to separate groups of containers every two weeks for ten weeks. After the herbicide application at 10 weeks, 40 seeds of creeping woodsorrel and flexuous bittercress each were applied to all containers. All herbicides provided effective control when seed were applied within 2 weeks of herbicide application. Herbicides containing oxyfluorfen or flumioxazin provided effective preemergence bittercress and creeping woodsorrel control when seed were applied up to 8 to 10 weeks after herbicide application. Other herbicide products resulted in reduced control as the time between herbicide and seed application increased. Index words: weed control, container crops, substrates. Species used in this study: flexuous bittercress (Cardamine flexuosa With.), creeping woodsorrel (Oxalis corniculata L.). Chemicals used in this study: pendimethalin (Pendulum 2G), prodiamine + isoxaben (Gemini G), pendimethalin + oxyfluorfen (OH2), and flumioxazin (BroadStar).

Influence of Pine Bark Substrate Age on Performance and Leaching of Nursery Preemergence Herbicides

The objective of these experiments was to determine if preemergence herbicides perform similarly across pine bark that was aged for varying lengths of time including 0, 4, 8, and 12 months after bark removal from harvested trees. Three preemergence herbicides were evaluated for three separate weed species, including 1) Cardamine flexuosa With. (bittercress) with isoxaben, 2) Digitaria sanguinalis (L.) Scop. (large crabgrass) with prodiamine, and 3) Oxalis stricta L. (woodsorrel) with dimethenamid-P. Leaching of herbicides through substrates was evaluated for prodiamine. Weed growth in the various substrates was variable, but few differences were detected in weed growth among the pine bark substrates evaluated. For isoxaben and prodiamine, weed control was similar among the pine bark substrates in most cases when label rates were applied. Although some differences were detected in prodiamine performance across different pine bark ages, a high level of control was achieved in all cases at rates well below manufacturer recommendations. Prodiamine leaching was minimal in all substrates. It would be recommended that growers test substrates for physical properties before use so that irrigation and other production inputs could be modified if needed. In most cases, growers should expect similar performance of preemergence herbicides regardless of pine bark substrate age.

Fine-scale ecological and transcriptomic data reveal niche differentiation of an allopolyploid from diploid parents in Cardamine

Polyploidization, or whole genome duplication, is one of the major mechanisms of plant speciation. Allopolyploids (species that harbor polyploid genomes originating from hybridization of different diploid species) have been hypothesized to occupy a niche with intermediate, broader, or fluctuating environmental conditions compared with parental diploids. It remains unclear whether empirical data support this hypothesis and whether specialization of expression patterns of the homeologs (paralogous gene copies resulting from allopolyploidization) relates to habitat environments. Here, we studied the ecology and transcriptomics of a wild allopolyploid Cardamine flexuosa and its diploid parents C. hirsuta and C. amara at a fine geographical scale in their native area in Switzerland. We found that the diploid parents favored opposite extremes in terms of soil moisture, soil carbon-to-nitrogen ratios, and light availability. The habitat of the allopolyploid C. flexuosa was broader compared with those of its parental species and overlapped with those of the parents, but not at its extremes. In C. flexuosa, the genes related to water availability were overrepresented among those at both the expression level and the expression ratio of homeolog pairs, which varied among habitat environments. These findings provide empirical evidence for niche differentiation between an allopolyploid and its diploid parents at a fine scale, where both ecological and transcriptomic data indicated water availability to be the key environmental factor for niche differentiation.Significance statementPolyploidization, or whole genome duplication, is common in plants and may contribute to their ecological diversification. However, little is known about the niche differentiation of wild allopolyploids relative to their diploid parents and the gene expression patterns that may underlie such ecological divergence. We detected niche differentiation between the allopolyploid Cardamine flexuosa and its diploid parents C. amara and C. hirsuta along water availability gradient at a fine scale. The ecological differentiation was mirrored by the dynamic control of water availability-related gene expression patterns according to habitat environments. Thus, both ecological and transcriptomic data revealed niche differentiation between an allopolyploid species and its diploid parents.

Early Postemergence Control of Woodland Bittercress (Cardamine flexuosa With.) and Yellow Woodsorrel (Oxalis stricta L.) with Dithiopyr and Isoxaben Combinations1

The objective of this research was to evaluate dithiopyr and isoxaben combinations and indaziflam (Marengo) for early postemergence control of woodland bittercress (Cardamine flexuosa) and yellow woodsorrel at 4 different early growth stages. Herbicides evaluated included sprayable formulations of isoxaben, dithiopyr + isoxaben, dithiopyr, indaziflam, and prodiamine + isoxaben without any surfactants. Woodland bittercress growth stages included seed production (extra-large), recently flowered (large), 6 to 9 leaf (medium) or in 2 to 5 leaf stage (small), while yellow woodsorrel growth stages included 8 to 12 leaf stage (extra-large), 4 to 6 leaf stage (large), 2 to 4 leaf stage (medium) and cotyledon to 1 leaf stage (small). Shoot fresh weight data showed all treatments provided ≤98% of woodland bittercress at the small stage. Dithiopyr + isoxaben (98%), isoxaben (90%), and indaziflam (93%) provided the highest level of woodland bittercress control at the medium stage and were the only treatments providing acceptable control (≥80%). In the large stage, dithiopyr + isoxaben provided acceptable control (80%) and outperformed other treatments. All treatments with the exception of isoxaben generally provided acceptable control of yellow woodsorrel up to the large growth stage. Only indaziflam (86% control) provided acceptable control at the extra-large stage. Index words: herbicide, postemergence weed control, container-grown plants, phytotoxic damages. Herbicides used in this study: isoxaben (Gallery® 4SC) N-[3-(1-ethyl-1-methylpropyl)- 5-isoxazolyl]-2,6-dimethoxybenzamide; dithiopyr (Dimension® 2EW) S,S'-dimethyl 2-(difluoromethyl)-4- (2-methylpropyl)-6-(trifluoromethyl)- 3,5-pyridinedicarbothioate; indaziflam (Specticle® FLO) N-[(1R,2S)-2,3-dihydro-2,6-dimethyl-1H-inden-1-yl]-6-(1-fluoroethyl)-1,3,5-triazine-2,4-diamine; prodiamine + isoxaben (Gemini® SC) 2,4-dinitro-N3,N3-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine + N-[3-(1-ethyl-1-methylpropyl)- 5-isoxazolyl]-2,6-dimethoxybenzamide; dithiopyr + isoxaben (Dimension® + Gallery®) S,S'-dimethyl 2-(difluoromethyl)-4- (2-methylpropyl)-6-(trifluoromethyl)- 3,5-pyridinedicarbothioate + N-[3-(1-ethyl-1-methylpropyl)- 5-isoxazolyl]-2,6-dimethoxybenzamide. Weed species evaluated: woodland bittercress (flexuous bittercress) (Cardamine flexuosa With.); yellow woodsorrel (Oxalis stricta L.).

Parboiled Rice Hull Mulch in Containers Reduces Liverwort and Flexuous Bittercress Growth

Use of preemergence herbicides for weed control is not always possible; some crops and many enclosed production sites are not labeled for herbicide applications. The objective of this research was to determine the utility of parboiled rice hull mulch for controlling two of the most common weeds in nursery crop production, flexuous bittercress (Cardamine flexuosa With.) and liverwort (Marchantia polymorpha L.). Two experiments were conducted to determine control of flexuous bittercress and liverwort with 0, 0.6, 1.3, or 2.5 cm (0, 0.25, 0.5, or 1.0 in) depths of rice hull mulch applied to the surface of 15 cm (6 in) diameter pots on a greenhouse bench. In both experiments, one group of containers were potted each with a single rose (Rosa ‘Radrazz’) and another group was not potted (only substrate and rice hull mulch). Flexuous bittercress seed and liverwort gemmae were applied to the surface of the substrate or mulch. Rose response and weed growth were monitored for 8 weeks in both experiments. Substrate pH, rose foliar color, and rose growth were not affected in either experiment. Flexuous bittercress and liverwort establishment and subsequent growth decreased with increasing rice hull depth. Containers with either a 1.3 or 2.5 cm (0.5 or 1.0 in) depth of rice hulls provided nearly 100% weed control. Rice hulls provided effective bittercress and liverwort control for 8 weeks with no adverse effects on roses.