Milium effusum (Poaceae: Poeae: Miliinae): species of systematic and cytological interest with notes on polymorphic nature and cytogeography

Present communication records polymorphic and polyploid nature of the forest grass species M. effusum having wide distribution over different continents and countries. Globally the 4 x plants are widely distributed. The West Himalayan plants, collected at 3000 m alt. and more, are also sporting chromosome number of 2n = 28 based on basic number of x = 7. Further meiotic course analysis of Western Himalayan plants follows diploid like behaviour possibly directed by diploidization. This communication also calls the attention to cytogeography of intraspecific cytotypes of M. effusum, where diploid plants (2n = 14) have also been reported, but only 2 times – from the Kola Peninsula, Russia and from the Switzerland mountains. Perhaps these are relict populations, which deserve to be proved, studied and protected.

Why is reproductive isolation between intraspecific cytotypes so important? A commentary on: ‘Strong post-pollination interactions govern cytotype isolation in a tetraploid–octoploid contact zone’

This article comments on: Mariana Castro1, João Loureiro, Brian C. Husband and Sílvia Castro, The role of multiple reproductive barriers: strong post-pollination interactions govern cytotype isolation in a tetraploid–octoploid contact zone, Annals of Botany, Volume 126, Issue 6, 2 November 2020, Pages 991–1003, https://doi.org/10.1093/aob/mcaa084