I wrote in this post about the odd behavior of common madia, Madia elegans, which I grew and planted for the first time this year, to try to establish a self-maintaining population around our property. Some plants remained smallish and others became thugs - but they all got the proper pretty Madia elegans yellow flowers -
Well I talked to a very experienced botanist and gardener from our local CNPS chapter and she said that - that's just what they do. In thin soil and dry conditions it gets two to three feet and with thinnish stems, which is what I saw on the hill nearby where it grows natively. But when they get lots of water and good soil (as the ones in the corner next to my neighbor's well irrigated fruit trees did), they just turn into gigantic thugs, very similar to the much more weedy and less attractive Madia sativa - which does grow around here, unfortunately.
I also note that after it has done buking up like the Hulk on steroids - it falls over!
So - word to the wise! Keep your Madia elegans on a strict diet if you want it to behave!