The Family Beds

The family beds being prepared in 2004. Viewed from the north, from the Palm House walkway
The Order or Family Beds at the National Botanic Gardens demonstrate the relationships between plants. The collection represents some 90 of the more important families flowering plants which are hardy in Ireland. Horticultural hybrids and cultivars are not grown here.

map of the beds Each flower bed contains members of a single or pair of closely related families - viewed in this manner it becomes possible to learn how each of these natural families is recognised. Formerly the beds were arranged in a sequence developed by Bentham and Hooker in 1854. Today we have reorganised the beds to reflect a modern understanding of the evolutionary relationships according to recent discoveries, especially at the molecular level. These findings indicate that there have been four main evolutionary radiations (see map at right).

A quick overview of the beds is available here, or a more detailed summary.

A complete listing of the species in the family beds is also available.

There are essentially five groups of plants displayed in the Order beds. You should begin your journey at the sundial end.
Hover the mouse over the pictures to see more than a single example of flowers in the grouping.

Paleotrees and Paleoherbs

Magnolia (top left) and Waterlily (top-right) 
Calycanthus (bottom left), 
Laurus nobilis (middle)
Drimys (bottom right)

Magnolia (top left) Waterlily (top-right). If you move your mouse over the image, you will also see other members of this ancient grouping which are characterised by their spirally arranged petals.

On the lawn by the Sundial are a Magnolia and a member of the Laurel fmily. These trees evolved very early on in flowering plant evolution, and we refer to them as belonging to the Paleo-trees (Ancient trees). On the surrounding lawns are four smaller beds, which represent the Paleo-herbs (Ancient herbs) these are non-woody plant families including waterlilies, Aristolochias and the Pepper Family (Piperaceae).

Remarkably Magnolia flowers are still almost identical to those of trees that were growing 80 million years ago. Along with Waterlilies, the flowers of Magnolia are still pollinated by beetles, these were the only herbivorous flying insects that existed at the time, butterflies, moths, bees and wasps only evolved much later.


                         Buttercup (above)
Carrot family (left) roses (middle)

Apart from the monocotyledons (see below) all the remaining flowering plants evolved from a Buttercup-like ancestor. Fowers from this group have separate petals that can be pulled off the flower one at a time. Unlike the Paleo-trees, paleo-herbs and monocots, all the species in these groupings have pollen grains with 3 pores and not a single pore.

The initial beds - buttercups, poppies, along with the Cabbages (Brassicaceae) and Violets (Violaceae) have separate stamens, while in families like the Mallows (Malvaceae) the anthers are fused into bundles. The Geraniums (Geraniaceae), Impatiens (Baslsaminaceae) and Oxalis (Oxalidaceae) have their stamens fused to the base of the flower. The Peas, Roses and Passionflowers have the stamens fused to the Calyx. As you progress through these beds the number of flower parts reduces, and the ovaries move from being above the flower in Buttercups, to being completely hidden and below the flower in Fuchsias (Onagraceae) and the Carrot family (Apiaceae).


daisy family (top left), 
campanula (below), common toadflax (right) The Asterids have their petals fused together, making a tubular flower. The Daisy family (Asteraceae), Campanulas (Campanulaceae) and Valerians (Valerianaceae) have ovaries that lie below the flower, while in the Heather family (Ericaceae) onwards, the ovaries are contained inside the corolla tube. The Heather and Primrose (Primulaceae) families are characterised by having twice as many anthers as petals. From the corner bed onwards all the flowers have an ovary with just two compartments. Families like the mints at the very end of these beds have the fewest number of floral parts, with just 2 or 4 anthers per flower. These flowers are very specialised in terms of pollination, ensuring the bee carries pollen on very small areas of her body, thus making cross-pollination efficient and highly economic.

Saxifragales and Caryophyllids

Paeony family (top) 
Saxifrages (bottom left) Caryophyllaceae (right) These families lie to one side of the rosids because although they share an ancient ancestry with them they have a very different evolutionary history. Most are herbaceous and those that are woody have anomalous secondary growth. The pinks and catchflys (Caryophyllaceae) are closely related to the docks and knotweeds (Polygonaceae). The ovary either has a central axis on which the ovules are borne, or these are all basal. They divide into two main groups - those with curved embryos in their seeds (Amaranthaceae, Cactaceae, Caryophyllaceae and Chenopodiaceae) or those with straight embryos (Plumbaginaceae and Polygonaceae).

The Saxifrages used to be classified close to the Rosaceae, while Paeonies were at one time placed with the Buttercups (Ranunculaceae). We now know they are better placed together, characterised by their half fused ovaries.


Alismataceae and Orchidaceae (top row)
Liliaceae, Poaceae, Iridaceae (Below) the monocots all share the single-pored pollen grains of the Magnolias and Waterlilies (Paleotrees and Paleoherbs).

Besides having their flower parts in multiples of threes, one of their chief characteristics is that they are unable to grow secondary wood - this means that the tree-like species cannot thicken their stems each year. Thus the herbaceous habit is the dominant growth form. Evolution in monocots has particularly favoured the rhizomatous and bulbous groups such as lilies, irises and gingers.

Grasses and sedges, with their growing points at ground level, and wind-pollinated flowers are the basis of nearly all non-forest vegetation throughout the world.