Introduction
“We begin with a discussion of some basic plant ecology.
Much of this is material that I have covered in workshops I have run over the years, especially those run under the title of ‘The Rabbit’s Eye View’. Having an understanding of these issues provides a background to effective understanding of the data provided for individual species and cultivars.
It is also an attempt to satisfy those many people who have asked me when I’m writing a book covering the material I have dealt with in the workshops. There may well be a book one day still, but at least here is the core material.
Understanding basic plant ecology is essential to understanding how plants perform in designed plantings, and part of the aim of this project is to present data on plant performance which is informed by plant ecology science.”
A continually refined plant directory
The plant directory started by pulling together material from existing sources and adding Noel’s own observations; the results of many years growing the plants, or if not growing them himself, knowing those who have grown them, or having made observations in gardens and nurseries.
All of this can of course be continually refined, and it is Noel’s intention to actively seek the observations of others which can be added.
So, we have the outline descriptions of the species covered, notes on their architecture – an area of description which is something of a novelty and their long-term performance.
Over time, Noel hopes to add material on the natural habitats and ecology of species covered, the value of the plants for fauna, and more references to further reading. As well as continuing to add new insights, observations and evidence from a range of sources.
All this, hopefully with the help of collaborators.
This directory defines the edges of its territory as being hardy herbaceous perennials, generally avoiding anything unable to cope with colder than USDA hardiness zone 7.
In time, and perhaps with the help of collaborators, it can be extended to cover some categories of woody plants, and those from warmer climates.
What is and is not included in the directory
Since there is a definite bias towards practitioners of ecological plantings, it largely excludes those plant groups that were the mainstay of traditional horticulture and in many cases need a more intensive management regime than most of us are now prepared to give them, e.g. bearded irises, delphiniums, chrysanthemums.
The plant directory focusses on natural species and the cultivars, seed strains and hybrids that have been around for a few decades and therefore become 'tried and tested'. Noel has a deep suspicion of new cultivars that are clearly launched for commercial reasons, very often with a PBR. Nothing against PBR in principle, but Noel objects to it being used by businesses as a way of 'cornering the market' in the presentation of some novelty to the public. Many PBR plants are also, Noel suspects, physiologically compromised and might therefore not survive the rough and tumble of the ecologically-managed border or, as with the hideous double Echinacea now on the market, are useless for pollinators, or just plain hideous.
Perennial Growth Forms
Herbaceous perennials include a very wide variety of growth forms.
As a category they vary far more than trees (so typically a trunk, branching at height) and arguably shrubs.
Herbaceous perennials blur into semi-woody species on hand (e.g. Erysimum), various species with persistent but non-woody growth (e.g. Dianthus) and cushion plants (e.g. Androsace). Herbaceous plants however defy easy categorisation.
For the purposes of this project, in its initial format, the stress is on truly herbaceous species, which do not have persistent dormant season growth, or if they do, it is not woody.
The only exceptions are those that keep their leaves during the dormant season, such as Liriope, but note this has no stems above ground during winter. Cauline Helleborus of course have an overwintering stem, but this does not form woody growth.
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Longevity
Perennial, is not easily defined. Easier perhaps to say what is not included: annuals (which includes those annuals that stagger on into a second year) and biennials. Many of the latter have a tendency to sometimes last more than two years, and include such familiar garden plants that are treated as 'honorary perennials' - foxgloves and mulleins, as well as many umbellifers, i.e. Apiaceae. To be included.
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Understanding what grows on underground
The easy categorisation of herbaceous perennials has defeated me and many others. The solution has been to look underground. The late Prof. Łukasiewicz is the only person, in my opinion, to have produced a coherent explanatory model of perennial growth.
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Succession
Succession is a key issue in plant ecology. I believe that understanding this gives us an exceptionally good framework for appreciating plant growth in both natural and managed situations.
