I've had one of these for years, just sat on a windowsill, doing its thing. Its flowered constantly for around 4 years with nice red flowers but this year I figure, it got bored and now it has yellow flowers! Anyone ever known this before?
Re: thorny plant with red-ish small flowers? It's a response to depletion of minerals in the soil. If you repot it (carefully, of course) into fresh soil, you'll see it return to the red flowers.