The Kalanchoe genus 

vary from odd to interesting and beautiful succulent plants.  For the most part popular.  However there are a few species that are very hardy and grow  easy from leaves or any piece of vegetation so that they are seen as weeds.
Kalanchoe bossveldiana,  could be the most popular
species cultivated for beautiful flowers here in the Republic of South Africa.  The plants are mostly sold in pots but they do best hanging.
Here on my rock garden wall the pink flowering one is 
so pretty I bought the yellow flowering one this year. 
There is a bright red one growing wild in the Kavango area. I must add an update photo some time

I am looking forward to the yellow flowering Kalanchoe
blooming as nice as the pink one next year.

The hanging aloes on the wall are a small species one from Madagascar to the left of the pink blooms.  Then to the right three Aloe pendens from Yemen followed by a few Aloe hardii from South Africa.