Do Plants Evolve Continuously Or In a Big Bang?

In THIS ARTICLE the authors (many of whom are based in Bristol) explore the hypothesis that, like animals, plants have a higher capacity for innovation early on but later, not so much. The article is based on THIS PAPER in Nature. 

To do this they collected 548 traits of 400 living and fossil plants and plotted the 130,000 observations onto, what they call, a design space. Also on this design space, they plot the predicted traits of extinct shared ancestors.

Then it gets complicated - at least for me - and they produce diagrams such as the one below which have axes which I find difficult to contemplate. I think I know what they mean, but don't ask me to explain it! The Nature article excels in producing even more challenging diagrams. I am sure there is a logical explanation of what NMDS1 and NMDS2 is but I do not know what it is.

Correction - NMDS is "non-metric multidimensional scaling".

The two axes summarise the variation in anatomical design among plants. Coloured dots represent living groups while the black dots represent extinct groups known only from fossils. The lines connecting these groupings represent the evolutionary relationships among living and fossil groups, plus their ancestors, inferred from evolutionary modelling. (The chlorophytes and charophytes are marine and freshwater plants while the remaining groups are land plants. Angiosperms are flowering plants). Philip Donoghue et al / Nature Plants

The result of all this impressive data gathering and analysis is that plants have evolved continuously and not in an early "big bang". And the Animal Kingdom is no different.