Are you looking for specific reasons why a plant would show morphological variation in different environments? I'm not a botanist so I can't tell you specifics about plants, but I can tell you that you will see morphological variation even among organisms within a single species due to phenotypic plasticity. Differing selective pressures result in differential gene expression.

One example of a plant with very high phenotypic plasticity is Poison Oak (Toxicodendron diversilobum) which varies tremendously in its morphology, with large variation in characteristics such as leaf size, leaf waxiness, and growth type (vine vs. shrub vs. ground-cover) depending on environmental conditions such as rainfall, temperature, soil, and light.

I agree with Heather Smith and Andrea Claassen, environment and climate has certain effect on plant growth including morphological variation. following papers may help you.

https://pdfs.semanticscholar.org/4287/494970ae8ebbda8f92b2776634fd401c065e.pdf

Article Impact of habitat variability and altitude on growth dynamic...

I agree with Heather Smith

I agree with Heather, I am not a botanist too, but, I done a genetic research on the environment wildlife observations in Australia and overseas about human gene and cancer from 2007 and it's continuing. By this research, I found that the life stands between two poles or axis same as Earth and it has been appeared on the Earth from heavy to light Elements and by any alive skeleton changed it shows the atmosphere got more pressure. It means that The atmosphere was light and by increasing one or more Elements insert to atmosphere the pressure got increase and life skeleton has been stood under pressure and got smaller and tidy .

So, in my mind there are two different Environment conditions which it belongs to the Elements for e,g Indian ocean and Pacific ocean, except migrant the native wildlife systems are much different.

About answer to this question, I think, any alive factors moved from A to B it is compulsory before any act have to canalized both soil combinations about alive environmental genetic foundation structure. If we have cancer situation it belongs to this unknown life foundation structure. Today we have got many problem about our life ,because there is not any information about heavy and light elements are getting shared in the gene structure.

In as much as I agree with Heather Smith and fellow geneticist I can also tell you as a botanist that environmental conditions/climate change/difference in altitude could lead change in physiological process of plants e.g. conduction, photosynthensis etc...and subsequently lead to varying morphological morphological parameters in the same plant