Hymenolobus
procumbens
(oval purse) is an erect or spreading annual, to 30cm. The
petals are white, up to 10 mm long. The fruit is a silicula,
up to 4mm long and elliptic in shape. It is a common weed of
offshore islands, salt lakes and estuaries from Shark Bay to
Esperance. Flowers from July to September. Native to
southern Europe.
The genus Lepidium
has 27 species native to Western Australia and two (possibly
three) introduced. There is no easy way to separate native
from introduced species by visual means. The three weeds are
annual, biennial or short-lived perennials, flowering in
spring. The petals are very small, and generally not
obvious. The fruits are siliculas, 2-4mm long and flattened
at right angles to the narrow septum. L.
africanum
(common peppercress) is up to 70cm high. It has lanceolate,
toothed basal leaves. It is a weed of wasteland and verges
from Geraldton to Esperance. Native to Africa.
L.
bonariense
(peppercress) is up to 50cm high and has pinnate leaves. It
is found among granite rocks and in tuart woodlands, from
Perth to Albany. Native to South Africa.
Lepidium
africanum
, RR
Lobularia maritima (alyssum, sweet alison) is a perennial, up to 20cm with linear leaves and white or sometimes mauve petals, 2.5-3mm long. The fruit is a silicula, 3.5-4mm long, elliptical in outline and flattened parallel to the septum. It has one seed on each side of the septum, in contrast to Alyssum linifolium which has four to six seeds on each side. A native of Europe and west Asia, widely grown as a garden plant. It is found in wasteland and on verges, mostly in coastal areas, from Perth to Esperance. Matthiola incana (stock) is a densely hairy perennial herb, woody at the base, to 1m tall. The leaves are grey-green and linear. The petals are purple, pink or white, 20-30mm long. The fruit is a siliqua, 4.5 to 16cm long, slightly compressed. Flowers in spring. A garden escape, now found in limestone heaths from Cervantes to Mandurah. Native to western and southern Europe.
Lobularia
maritima
, RC
Raphanus raphanistrum (wild radish) is an annual herb, up to 1m tall. The leaves and stem usually bear bristly hairs and the petals are pale yellow, white or occasionally purple to lilac, 15-20mm long, often with dark veins. Fruit is a siliqua, constricted around the seeds, up to 8cm long. On ripening, the fruit breaks into single-seeded sections. Scattered around settlement sites from Exmouth to Geraldton and a very common agricultural, horticultural and roadside weed from Geraldton southwards. Economically one of the most important weeds of cropping in Western Australia. Flowers throughout the year but mainly in spring. Native to Europe.
Raphanus
raphanistrum
, RR
Rapistrum rugosum (turnip weed) PP is an annual herb, to 60cm. The stems and leaves are often bristly. The petals are yellow, 5-10mm long. The fruit has two segments: a cylindrical base up to 3.5mm long containing from none to two seeds, and a distinctive ridged, turban-shaped upper section containing a single seed. This is a major weed of cropping and pasture in eastern Australia, with the potential to spread more widely in Western Australia. It is found in several places in the wheatbelt, in wasteland, fire breaks and disturbed urban bushland. It appears to be spreading in the Dongara region. Native to Europe.
Rapistrum
rugosum, RR
Rorippa
nasturtium-aquaticum
(was Nasturtium
officinale)
(watercress) is a perennial aquatic plant, rooting at the
nodes of the stems. The leaves are pinnate, the petals
white, 3.5-7mm long and the flowers are produced in spring
and early summer. The fruit is a siliqua, up to 2cm long,
slightly curved; with seeds in two rows oneach side of the
septum. Found in disturbed wetlands, drains, seepages and
creeks from Geraldton to Albany. Introduced from Europe,
probably for its astringent leaves used in salads.
Two species of Sinapis
have been recorded occasionally within Western Australia,
and may be confused with the yellow Brassica species. They are more bristly on the leaves and
stems and have distinct ridges (veins) on the fruits. The
fruit of S.
alba
(white mustard, named after the seeds, not the flowers,
which are yellow) is a siliqua 2-4cm long, of which the
terminal 1-3cm is a flat, sabre-like beak. The fruit of
S.
arvensis
(charlock) is up to 6cm long, with a beak shorter than the
fruit. Occasional in the cropping belt. Both native to
Europe.
Rorippa
nasturtium-aquaticum
, RR
The Sisymbrium genus can be distinguished from most of the other yellow-flowered introduced crucifers by having oblong, sometimes irregularly shaped seeds, rather than the typical ball shape of seeds - as seen in Brassica, for example. They also have a siliqua without a well-defined beak, although the remains of the stigma will often be apparent. Five species, all annuals, are naturalised in Western Australia. S. erysimoides (smooth mustard) has the smallest flowers of all five species in Western Australia, with petals less than 2.5mm long. It grows up to 80cm tall and is virtually hairless. The fruits are up to 5cm long and straight. The stem below the pod is 5mm or less, shorter than the following species and more robust. An uncommonweed of grazed woodlands and shrublands in the southern part of the State. Native to southern Europe. S. irio (London rocket) has petals 2.5-3.5mm long and grows to 60cm. Fruits are somewhat curved, up to 6cm long on a narrow stalk 6-10mm long. Flowers in late winter and spring. A widespread weed of eastern wheatbelt crops, islands, grazed woodlands, shrublands and creeks in the southern part of the State. Native to southern Europe.
Sisymbrium irio , RR
S. officinale (hedge mustard) is distinguished by its fruits, which are held tightly alongside the stem and are only 1-2cm long. The whole plant is rough to the touch and is wiry when dry. Petals are 3-4mm long. A weed of agricultural areas in the south-west, it is native to the Mediterranean.
S.
officinale, RR
S. orientale (Indian hedge mustard) may reach 1m. Stem leaves are often distinctly arrow-shaped and the petals are 5-10mm long. It has fruits up to 11cm long. A widespread weed of the wheatbelt, it is sometimes also found in grazed woodlands on the coastal plain and is spreading along roadsides and disturbed areas in the arid zone. It is native to western Asia and the Mediterranean. S. runcinatum is a prostrate or ascending species to 50cm with petals 2.5-3.5mm long. It can be distinguished from other Sisymbrium species by the bracts surrounding the inflorescenceand its small, densely hairy, curved fruits up to 3.5cm long. An uncommon but widespread weed of verges and granite rocks in the southern part of the State.
S.
orientale
, RR
Succowia balearica is a very distinctive annual, naturalised in at least two places in Perth. The leaves are pinnately lobed and the plant sometimes twines. It has bright yellow petals, 7-10mm long and flowers in spring. Its fruit consists of a softly spiny, round fruittopped by a 2-3cm long beak. It may have the potential to spread considerably. Native to the Mediterranean.
Succowia
balearica, RR
