  Pollen grains represent the male gametes of seed plants and their viability
is critical for efficient sexual reproduction in the plant life cycle. Pollen
analysis is used in diverse research thematics to address a range of botanical,
ecological and geological questions. More recently it has been recognized that
pollen may also be a vector for transgene escape from genetically modified
crops, and the importance of pollen viability in invasion biology has also been
emphasized. In this work, we analyse and report an efficient visual method for
assessing the viability of pollen using digital holographic microscopy (DHM).
We test this method on pollen grains of the invasive Lantana camara, a well
known plant invader known to most of the tropical world. We image pollen grains
and show that the quantitative phase information provided by the DHM technique
can be readily related to the chromatin content of the individual cells and
thereby to pollen viability. Our results offer a new technique for pollen
viability assessment that does not require staining, and can be applied to a
number of emerging areas in plant science.
