GGplot2 in combination with Guide_legend arguments

Question

theme_pubr in the ggpubr package by default creates legends with the title on the side and the variables distributed horizontally. However,i'm trying to make a legend with the title on top and the species in one column.

I have tried using guides(colour=guide_legend(ncol=1)) and guides(colour = guide_legend(title.position = "top")) in combination, however one seems to override the other. Can anybody explain why this happens and how to work around it?

example code using the iris dataset.

library(ggplot2)
library(datasets)
library(ggpubr)



ggplot(iris,aes(Species, Petal.Length))+
  geom_point(aes(colour= Species))+
  theme_pubr()+
  labs_pubr()+ 
  guides(colour=guide_legend(ncol=1))+
  guides(colour = guide_legend(title.position = "top"))

Thanks in advance,

Stuart