Ms Davidson was against Minister for Women Julie Anne Genter. While a favourite, the overwhelming margin, 110-34, was decisive. Although the actual policies of the two women are not dissimilar, Ms Davidson was clearly identified as the candidate on the left.
The Greens range from staunch no-compromise supporters to those who can accept working within the system for gains. There are also differences between those who wish to emphasise environmental issues and those who insist social justice and left-wing matters are core Green policy. Many challenge capitalism itself.
The Greens are aware of the dilemmas and these would have been in the minds of members as they voted for their co-leader.
Backing MMP governments has been suicide for small parties. But what is the point of forever remaining a fringe Parliamentary group excluded from the levers of power?
Would support for Ms Genter allow the party to be differentiated sufficiently from the Labour-led Government? At the same time, the more radical Greens can be assuaged by Ms Davidson's election. Someone more to their liking is at the top.
Former co-leader Metiria Turei is herself socialist oriented and, as it happens, also Maori. There is a thread of a like-for-like swap.
Ms Davidson (44) will be able to stir and proclaim in a way Ms Genter as a minister could not. She will be able to highlight New Zealand First influences on Government the Greens object to.
Ms Davidson is inexperienced in Parliament, becoming a list MP in 2015. But she has worked as a Human Rights Commission adviser and as chief panellist on the Owen Glenn inquiry into domestic violence and child abuse. She is the daughter of Maori activists, her father being Whale Rider and Shortland Street actor Rawiri Paratene. She has six children.
Ms Davidson, who lives in Manurewa, Auckland, will endeavour to broaden Greens' support among the poor and Maori and Pasifika. That is a daunting task because most from those communities vote Labour or not at all.
The Greens' party vote in South Auckland, despite policies well to the left of Labour, is abysmal, with only 698 in last year's election in Manurewa. Most electoral support comes from the educated and professionals. Hence, party votes in seats like Wellington Central (9198 last year), Dunedin North and Auckland Central are the foundation for the Greens to continue to breach the 5% threshold and stay in Parliament.
Therein lies a quandary thoughtful Greens are well aware of. The well-off voters can be deeply concerned about environmental issues and are likely to be social liberals. But would firebrands from the left put them off? Just how big is the core that really cares about climate change, water quality and the like, while also believing in a sweeping re-ordering of the economic system?
Remember, too, though, that every party has underlying divisions and tensions. National's commitment to the centre must frustrate many in its ranks, even if they accept that is the route to power. And Labour's divisions are well-established, even if they are dimmed at present beyond the Ardern glow.
The Greens also know they and Labour draw from the same well. Soft Green support diverts to Labour without hesitation.
In electing Ms Davidson, the Greens will know they are taking risks. But, similarly, supporting Ms Genter was also risky, just in a more passive way.
After all, what did the Greens have to lose? They could well be fighting for their survival in Parliament.
