Flora of New Zealand Series

Annual to perennial herbs, rarely small shrubs. Hairs eglandular, simple, forked, branched or stellate. Lvs alternate, rarely opposite, exstipulate, simple or pinnatifid or pinnate to 2-pinnatisect. Infl. usually an ebracteate raceme, rarely bracteate, compact at flowering, usually elongating at fruiting, rarely a panicle or corymb or fls solitary. Fls hypogynous, usually ⚥, usually actinomorphic. Sepals 4, in 2 decussate whorls of 2. Petals 4, rarely 0, free, alternating with sepals, usually with a narrow erect claw and spreading limb. Stamens 6, a lateral short pair and 2 median long pairs, rarely 4, 2, or 0; filaments sometimes with a wing or tooth-like appendage. Lateral nectaries 4, usually free and paired beside bases of the lateral (short) stamens, sometimes each pair united between the ovary and the base of the short stamens; median nectaries 2, solitary outside bases of each median stamen pair, rarely 2-lobed, often 0; sometimes nectaries connate to form a ring around the receptacle. Ovary superior, of 2 fused carpels, usually 2-celled by false septum; placentation parietal; ovules 1-many. Stigma capitate or of 2 erect or spreading lobes. Fr. usually a capsule dehiscing by two 1-many-seeded valves, sometimes indehiscent, sometimes with an indehiscent seedless to many-seeded beak above the valves, sometimes lomentaceous with valvar portion seedless and rudimentary. Style and stigma persistent in fr. Seeds usually in 1 or 2 rows in each locule, non-endospermic. Embryo with radicle along edges of cotyledons (accumbent) or along the face of one cotyledon (incumbent) or incumbent with cotyledons longitudinally folded (conduplicate), rarely with more complex configurations.

The commonest habit in the Brassicaceae (alternative family name Cruciferae) is that of a taprooted herb with a basal rosette of entire to pinnate lvs and 1 or more erect, branching, leafy stems terminating in racemose infls. However spp. may be rhizomatous or stoloniferous and stems may be prostrate or ascending or scapose. A few are subshrubs.

The fls of the family are fairly constant but petals are sometimes 0 and the number of stamens may be reduced to 4, 2, or 0. The nectaries are variable in size, shape and position. The stigma is most frequently capitate but in some genera (e.g., Cheiranthus) it has 2 erect or spreading lobes, which may each be equipped with a horn-like process on the back as in Matthiola.

Considerable variation is found in the fr. (Fig. 44). The typical fr. of the Brassicaceae is a 2-valved capsule. When more than 3× as long as broad, this is termed a silique and when less than 3× as long as broad it is termed a silicle. The fr. is divided into 2 locules by a false septum, which is formed as an outgrowth from the 2 placentae, and within each locule the seeds may be in 1, 2 or rarely more rows. In some of the genera in which the fr. is a silique, the base of the style may be conic or expanded above the valved part of the fr. and is then called a beak. Such beaks often contain 1-several seeds (e.g., in Brassica spp., Hirschfeldia), but in a few genera (e.g., Raphanus) all the seeds are contained in the greatly enlarged beak and the valved part of the fr. Is reduced to a seedless rudiment at the base of the silique. Beaks are not usually present on silicles and are therefore not mentioned in descriptions of genera with silicles. The configuration of the embryo within the seed is often a useful character in the family.

380 genera, 3200 spp., cosmopolitan especially temperate and Mediterranean regions.

Mustard oils or glucosinolates are accumulated in the tissues of many crucifers, especially in the roots, lvs and seeds. These are sulphur compounds and their degradation products give the distinctive aromas and flavours of the family. They are found in only a few other families (e.g., Resedaceae, Tropaeolaceae).

The Brassicaceae includes some important temperate vegetables (e.g., cabbage, turnip) and fodder plants (kale) and some important weeds (shepherd's purse, wild turnip, hoary cress). A few genera (e.g., Cheiranthus, Arabis, Iberis, Matthiola) contain ornamentals.

Several genera of Brassicaceae can be recognised by features which are unique or at least not found among other N.Z. members of the family: lvs smelling of garlic when crushed - Alliaria; silique dehiscence explosive by coiling elastic valves - Cardamine; petals deeply 2-fid - Erophila petals unequal - Iberis; silicle large, strongly flattened, septum silvery - Lunaria.

Fig. 44. Brassicaceae frs. A Cakile edentula; B Brassica rapa; C Lunaria annua; D Raphanus raphanistrum subsp. raphanistrum; E Sisymbrium orientale; F Barbarea intermedia; G Lepidium sativum; H Hirschfeldia incana; I Capsella bursa-pastoris; J Alyssum alyssoides; K Coronopus didymus. © All rights reserved. [Image: 4X53]