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Manual of the New Zealand Flora.

[Introduction to Order III. Cruciferæ.]

Herbs, very rarely undershrubs, with pungent watery juice-Leaves alternate, entire lobed or pinnately divided, the lower ones often forming a rosette at the base of the stem; stipules wanting. Flowers perfect, in terminal racemes, which are often short and corymb-like when the flowering commences, but lengthen out as it advances, usually without bracts. Sepals 4, free, deciduous. Petals 4, free, hypogynous, placed cross-wise. Stamens 6, 2 of them shorter than the other 4; sometimes reduced to 4 or even 2 (Lepidium). Ovary usually 2-celled; style short or wanting; stigma entire or 2-lobed. Ovules few or numerous. Fruit a pod, long or short, usually divided into 2 cells by a thin partition called page 31the replum, from which the 2 valves fall away at maturity; more rarely the pod is indehiscent or transversely jointed. Seeds without albumen, entirely filled by the large embryo, which is variously bent or folded, the radicle either lying along the edges of the cotyledons (accumbent) or placed along the back of one of them (incumbent).

The Crucifers form a large and extremely natural family, comprising about 180 genera and between 1500 and 2000 species. The species are distributed over the whole world, but are most plentiful in the temperate regions of the Northern Hemisphere, and especially so in southern Europe and Asia Minor. They are rare in the tropics, particularly where there are no mountain-ranges. Most of them possess antiscorbutic and stimulating properties, and many are staple articles of food. Not a few of the cultivated species (and others) have become naturalised in New Zealand, as will be seen from the list of introduced plants appended to this work. Of the New Zealand genera, Pachycladon and Notothlaspi are endemic; the remainder are widely spread outside the colony.

* Pods long and narrow.

Pods terete, linear-oblong, tumid. Seeds in two rows in each cell. Cotyledons accumbent 1. Nasturtium.
Pods flat, linear, acute; valves opening elastically from the base. Seeds in one row. Cotyledons accumbent 2. Cardamine.
Pods terete or obtusely 4–6-angled, 1–3-nerved. Seeds in one row. Cotyledons incumbent 3. Sisymbrium.

** Pods short and broad.

Alpine herb with stellate pubescence. Pods compressed, boat-shaped, not winged. Seeds 3–5 in each cell 4. Pachycladon.
Pods compressed, oblong to obcordate, valves turgid, keeled. Seeds numerous 5. Capsella.
Pods much compressed, ovate to orbicular, often winged. Seeds 1 in each cell 6. Lepidium.
Alpine herbs with sweet-scented flowers. Pods large, much compressed, obovate, very broadly winged. Seeds numerous. 7. Notothlaspi.