Brassicaceae-Cress2017-08-17T14:20:36+00:00

Brassicaceae: Mustard Family — Cress

Members of the mustard family all have four petals, usually in a cruciform shape (hence Cruciferae; the old name for the family).  With some groups (particularly the mustards themselves (Brassica, Hirschfeldia, Sisymbrium, Caulanthus and Turritis)), it is necessary to pay close attention to the fruits.  Fruits in the Mustard family are of two kinds, siliques and silicles.  Siliques are typically at least 2 x as long as they are wide and silicles are not. Some siliques are more or less cylindric, others (as in the Wild Radish) are noticeably fatter at the base and taper towards the tip.  Some silicles are erect and appressed to the stem, others grow outwards and curve upwards or outwards and curve downwards.  Recognizing these different characteristics makes it much easier to identify species which may have very similar flowers.

Milkmaids / California Toothwort – Cardamine californica

Blooms:

Jan–May

Plant Height:

27–70 cm

Flower Size:

Medium

Origin:

Native

Habitat:

Shaded sites, woodland

Notes:

One of the most common shade-loving plants blooming in early spring.  It has loose clusters of pure white (occasionally pink-tinged) 4-petalled flowers on distinct pedicels.  Leaves have 3–5 leaflets of varying shapes, from narrow to arrow-shaped though broad to rounded, sometimes with small but distinct lobes.

Hairy Bitter-cress – Cardamine hirsuta

Blooms:

Feb–July

Plant Height:

10–35 cm

Flower Size:

Very small

Origin:

Native

Habitat:

Shaded sites, woodland

Notes:

Similar to Western Bitter-cress (Cardamine oligosperma) but most easily distinguished by a close examination of the flowers.  Hairy Bitter-cress has 4 (occasionally 6) stamens, Western Bitter-cress consistently has 6.  Also, the petals of Hairy Bitter-cress are narrower although this can be difficult to determine without a direct comparison. Fruits are erect cylindric siliques (20–25 mm long). The petioles of its leaves have hairy margins. The leaves themselves are round to kidney-shaped with cauline leaves being smaller and sometimes narrower. A very common weed.

 Heart-podded Hoary Cress / Whitetop – Lepidium draba

Blooms:

Apr–Aug

Plant Height:

20–65 cm

Flower Size:

Medium cluster

Origin:

Europe

Habitat:

Disturbed areas, pastures, fields

Notes:

The plant has a stout, erect, branched stem.  Cauline leaves are 3–9 cm long, ovate to obovate and widely spaced. The inflorescence is slightly domed with individual flowers on pedicels of varying lengths. Petals are white, clawed and 2 x sepal length.  Fruits are flat, heart- to kidney-shaped, the top neither winged not notched.

Mouse-ear / Thale Cress – Arabidopsis thaliana

Blooms:

Feb–May

Plant Height:

6–30 cm

Flower Size:

Very small

Origin:

Eurasia

Habitat:

Disturbed ground, sandy areas, flats, fields

Notes:

An uncommon cress, found on Fort Ord.  It has diminutive white flowers with 6 stamens and 4 petals.  Fruits are spreading to ascending, cylindric siliques, 1–5 cm long, hairless and unsegmented, borne on  distinct pedicels. It has a well-formed basal rosette of hairy leaves.

Shepherd’s Cress – Teesdalia nudicaulis

Blooms:

Feb–May

Plant Height:

5–15 cm

Flower Size:

Very small

Origin:

Europe

Habitat:

Disturbed areas

Notes:

An uncommon cress, to be found on Fort Ord.  Like Mouse-ear Cress (Arabidopsis thaliana), it has diminutive white flowers clustered at the stem tips, each with 6 stamens and 4 unequal petals.  The fruit is a silicle (quite different from the siliques found on Mouse-ear Cress), heart-shaped to round with a shallow notch at the tip.  There are two seeds in each chamber (an important diagnostic feature).  Leaves are in a well-formed basal rosette, glabrous and entire or irregularly lobed.

Watercress – Nasturtium officinale

Blooms:

Mar–Nov

Plant Height:

1–11 dm

Flower Size:

Small

Origin:

Europe

Habitat:

Streams, springs, marshes, lake margins

Notes:

Commonly found in or by streams in sometimes dense mats, this has small clusters of white flowers. Stems can be long but are weak and mostly prostrate, rooting at nodes. Leaves are pinnately parted with 3–9 round to lanceolate leaflets which have a peppery taste. Fruits are cylindric siliques, straight or up-curved and narrowed between individual seeds.

Western Yellow Cress – Rorippa curvisiliqua

Blooms:

Mar–Sept

Plant Height:

10–40 cm

Flower Size:

Medium cluster

Origin:

Native

Habitat:

Streambanks, seeps, mud flats

Notes:

Much branched from its base. The basal leaves are not rosetted and are noticeably toothed.  Cauline leaves are pinnately lobed. The inflorescence is elongated. The conspicuously upturned siliques are distinctive, giving the species its scientific name.

American Winter Cress – Barbarea orthoceras

Blooms:

Mar–July

Plant Height:

20–60 cm

Flower Size:

Small

Origin:

Native

Habitat:

Moist places, usually above 700 m

Notes:

Closely related to the mustards but the glabrous leaves and the pinnately lobed leaves subtending the flower heads are distinctive as is the vivid green coloring. There is also a basal rosetted of leaves with 2–4 pairs of lobes.