The guide provides plant profiles and identification tools for many of the cultivars of every plant – native and exotic – growing in Victoria, South Australia, Tasmania, New South Wales and south-eastern Queensland.

It includes written descriptions of the plants, their origins and general history, and contains illustrations that highlight a plant's identifying features. There are also botanical keys for those who want to follow a sequence of identification steps and the names of parks and gardens where you can see some of the plants growing.

Encyclopedic in its approach, the online flora digitises the information contained in the five-volume, 2700-page Horticultural Flora of Southeastern Australia and thereby makes what is a cumbersome and expensive (and out-of-print) tome freely accessible.

On the upside it's more fail-safe than consulting a plant-identification app and more comprehensive than any printed plant guide. On the downside, it does require a degree of botanical knowledge. In order to access information about any plant you need to know at least some part of its common, Latin or family name.

Tim Entwisle​, the RBG Victoria's director and chief executive, envisages some people will use the site in tandem with other plant-identification methods, such as photographic apps and hard copy guides.

In order to broaden the site's reach, plant photographs are being regularly uploaded and, ultimately, Entwisle would also like the site to include the means by which you could search for plants without knowing their names, such as by plant features or climatic conditions.

Such measures would further set this apart from traditional – book-form – horticultural flora, of which there are only three other substantial ones in the world, including for North America, Europe and Hawaii and the tropics. Another one concentrating on Spain is about to be completed.

The move follows the RBG's 2016 digitisation of the four-volume Flora of Victoria which details the 3700 native and naturalised plants growing in the wild, and is part of Entwisle's push to boost knowledge about the nature surrounding us.

"Knowing about plants helps us understand nature and the world. It means we make better decisions – about what to grow in our gardens, about what improves biodiversity and what leads to a better world," he says.

Entwisle says naming plants is part of our cultural "story-telling". "My father called half a dozen plants 'japonica' and it was not always that botanically accurate but he could communicate with me and with the neighbours and I think that has been lost."

By digitising the Horticultural Flora of Southeastern Australia, which was published over the course of a decade ending in 2005, it has been possible to breathe new life into a project that took years of research and provides a fount of information. As an online entity that can be updated, modified and carried around on a phone, it can speak to us all.

Horticultural Flora of Southeastern Australia is at hortflora.rbg.vic.gov.au; Flora of Victoria is at vicflora.rbg.vic.gov.au.