The Goodeniaceae of Western Australia

The Goodeniaceae is a family with a very clear centre of diversity in Australia. Small numbers of species in five genera occur in South-east Asia, the Caribbean, South Africa and the islands of the Pacific, but the vast majority of species are Australian, as are the majority of species in those genera that occur outside Australia.

Western Australia in turn is a centre of diversity within Australia for most genera, with 228 described and 27 undescribed (phrase-named) species recognized in the State.

This key includes all described and phrase-named taxa in Western Australia, in the following genera:

  • Anthotium (4 species and 2 informal species)
  • Brunonia (2 species and 2 informal species)
  • Coopernookia (3 species)
  • Dampiera (55 species and 5 informal species)
  • Diaspasis (1 species)
  • Goodenia (122 species and 11 informal species)
  • Lechenaultia (27 species)
  • Pentaptilon (1 species)
  • Scaevola (56 species and 7 informal species)
  • Selliera (1 species)
  • Velleia (13 species)
  • Verrauxia (3 species)


A typical Goodeniaceae flower showing the bilaterally symmetric flower and pollen presenter
 

Members of the family can usually be recognized by a combination of bilaterally symmetric flowers, petals with a firm central portion and distinctly thinner lateral wings, and an unusual cup-shaped structure (the indusium) surrounding the stigma at the style end. The indusium is universally and uniquely present in Goodeniaceae, while the other characters are absent or poorly developed in some genera.

Habit. All members of the family are small, relatively soft-wooded shrubs or herbs. Herbs are defined here as small plants with pliable, non-woody, herbaceous stems (if they have stems at all). Shrubs have woodier stems and are always branched.

Stems in Goodeniaceae may be cylindrical and smooth or shallowly to distinctly ribbed. The stems are often covered with a sparse to dense indumentum of hairs. These may need to be removed by scraping to determine if the stems are ribbed or unribbed.

In a few taxa the stems are distinctly flattened, with wing-like extensions on either side of the core stem.

Leaves in all species are arranged alternately along the stem. If the stem is very short or absent the leaves are usually arranged in a rosette or cluster. Some species have both rosette and stem leaves; in this case the rosette leaves are generally larger, while the stem leaves often grade into leaf-like bracts. When measuring leaf dimensions, choose the largest fully-developed leaves available on the specimen. The key’s scoring accommodates both rosette leaves and stem leaves when present, but reduced, leaf-like bracts have not been measured.

Leaves may be glabrous or covered in a sparse to dense indumentum of hairs. In a sparse indumentum the leaf surface is clearly visible between the hairs, while in a dense indumentum it is almost or fully obscured.

The hairs making up the indumentum may be simple (unbranched), glandular (simple hairs each with a knob-like gland at their apex), dendritic (branched or tree-like), or stellate (star-shaped). Some leaves are glabrous but the surface is covered in small papillae (short rounded bumps or projections).


Hairs on leaves and stems of Goodeniaceae. From left to right: simple, stellate, dendritic and glandular hairs
 

In many taxa the hairs, if present, are all of one type. In some, several types of hairs (e.g. simple and glandular, or simple and stellate) are present. A mixed indumentum is usually best observed on young leaves near the stem apex.

Note that if a mixed indumentum is present, you may select two or more states in the indumentum characters. For example, if a specimen has a mixture of simple and glandular hairs, you may choose both simple and glandular for Leaf indumentum. Note however that this will return a list of taxa having either all-simple, all-glandular or mixed simple and glandular hairs. A useful strategy in these cases is to choose the option that returns the smallest number of taxa, then check the final identification to ensure that both hair types are present in the identified taxon.

Glandular hairs usually secrete a sticky, mucilaginous substance from their knob-like tip, when dense giving the whole plant a sticky feel.


Leaves in Goodeniaceae
 

Many species have shallowly to deeply toothed leaves, often with the teeth large and widely spaced. Some have entire leaf margins, while others are shallowly to deeply lobed (lobes are defined here as somewhat irregular, rounded extensions of the leaf margins, while teeth are generally more regular and usually have a more or less acute apex). If the leaves are very densely hairy it may be necessary to scrape the hairs from a portion of the leaf margin to check for teeth or lobes.

Flowers are borne singly or in few- to many-flowered inflorescences.

Two important characters to assess are the presence or absence of a pedicel and of bracteoles. Pedicels are short or long, distinct stalks joining the flower to the stem or inflorescence axis. Bracteoles are large or small, paired, leaf-like structures borne at the base of the flower or on the calyx. When pedicels are absent (the flowers are sessile), bracteoles will appear like a pair of leafy structures at each flower’s base. If bracteoles are present, measure their length and assess their indumentum (this will generally be similar to that of the leaves, but may differ)

In a few taxa, mainly those in the genus Dampiera, the calyx lobes are rudimentary (reduced to such extent that these are not apparent), or absent. If the flowers are hairy it is important to carefully remove the indumentum (hairs) before deciding that calyx lobes are absent, as they may simply be small and obscured by the indumentum.

The corolla comprises five white or coloured petals joined at the base into a tube that is split down one side to varying degrees. There are two distinct arrangements of the corolla lobes (petals):


Goodeniaceae flowers showing (left) equal corolla lobes and (right) unequal corolla lobes
 

  • equal. All five lobes are more or less equal in size and shape, and are not arranged in two distinct groups.
     
  • unequal. Three central or lower lobes are similar and form a distinct group positioned between or below two distinct outer lobes.

In many species with unequal corolla lobes, the outer lobes have distinct auriculate (ear-shaped) appendages part way along their length. In flowers before or at anthesis, the auricles are pressed together and cup the style-end indusium. It is important to carefully part the outer corolla lobes to check for the presence of auricles.


Goodeniaceae flowers from above showing (arrowed, left) auricles on the outer lobes and (arrowed, right) a corolla spur
 

Two species have a striking, horn-like spur projecting backwards from the base of the corolla between the sepals.

The corolla may be glabrous or hairy. Assess the indumentum of the inner and outer surface of the corolla separately. The indumentum on the outer surface is often restricted to the tube and the thicker, central portion of the lobes. This indumentum, as in the leaves, may comprise simple, glandular, dendritic or stellate hairs. The inner surface of the corolla lobes are either glabrous or simple-hairy (often with twisted or curly hairs).


Dissected flowers of Goodeniaceae showing (left) free and (right) connate anthers
 

The anthers, when the flower, opens may be free or united in a ring (connate) around the style. In general, the anthers remain free or connate after the flower opens and they begin to wither, but it is best to assess this character on recently-opened flowers.

As noted, the style-end forms a cup (indusium) enclosing the stigma. As the style elongates past the stamens immediately before the flower opens, pollen is deposited from the anthers into the indusium cup. Visiting pollinators are brushed with pollen from the indusium. Later, the stigma matures, grows out of the indusium and becomes receptive to pollen from subsequent visitors.


Indusia of various members of Goodeniaceae showing the wide variety of form and indumentum. All species here have single indusia
 

The indusial cup often bears dense hairs in various distinctive patterns, often forming a brush encircling the rim of the indusium with or without longer hairs on the back.


Two- and three-headed indusia (branched styles) are rare in Goodeniaceae, and distinctive for those species that bear them
 

In the genus Dampiera the pollen in the indusium is scanty and is usually presented on the auricles and on the outside of the indusium.

Most species have a single indusium on the style; in a small number of taxa the style is forked and bears two indusia, while Goodenia heppleana has a three headed indusium.

The ovary may be superior (with sepals and petals joined at its base), or partially or fully inferior (with sepals and petals joined part way along or at the apex). In some species the ovary may be gibbous (swollen or enlarged on one side).

There are one or two carpels (cells) in the ovary. The number of ovules in the ovary is an important feature: in some genera there is a single ovule per cell (i.e. one or two ovules per ovary), while in others there are more than two (often many) ovules. Ovules are best counted by carefully dissecting mature or slightly over-mature flowers.

The fruit may (depending on the number of ovules) form an indehiscent, dry nut or fleshy drupe (when there is one ovule per carpel), or a capsule opening in 2 or 4 valves (when there are several to many ovules per carpel). If the fruit is a capsule, the seeds are usually winged and have a mucilaginous coating that swells when moistened, aiding water uptake during germination.