Lepidium L.

Volume IV (1988) - Flora of New Zealand Naturalised Pteridophytes, Gymnosperms, Dicotyledons

LEPIDIUM L.

Annual, biennial or perennial taprooted herbs, sometimes subshrubby with stout woody rootstock, rarely shrubs. Hairs simple or papillate or 0. Stems prostrate to erect, leafy. Lvs simple, toothed or 1-2-pinnatifid, or pinnate. Racemes ebracteate. Sepals erect to patent, not saccate. Petals white, rarely yellow or reddish, or often 0. Stamens (0)-2-6, without appendages. Nectaries variable, 6 or 4, tuberculate or filiform. Style long, short or 0; stigma capitate. Silicle ovate, elliptic, obovate, circular or rhomboid, angustiseptate, dehiscent; valves keeled and usually winged, the wings forming a notch at apex and sometimes fused to the base of the style. Seeds ovoid, winged or not, 1 per locule.

Key

Dioecious

16. sisymbrioides

Stems usually many, < 1 mm thick, flexuous; stem lvs narrow-ovate to oblong, > internodes

subsp. sisymbrioides

Stems few, > 1 mm thick, not flexuous; stem lvs linear-lanceolate or broadly ovate to oblong, > internodes

Pinnae of basal lvs often lobed, linear, acute; midrib ⅕-⅛ lf width; cauline lvs acute, narrow-lanceolate, cuneate at base

subsp. kawarau

Pinnae of basal lvs usually simple, obovate or broadly lanceolate, obtuse; midrib 1/4-(⅓) lf width; cauline lvs obtuse, ovate to oblong, often with amplexicaul auricles at base

subsp. matau

Hermaphrodite

Stem densely papillate, puberulent, or pubescent

Stem glabrous at least below, rarely with a few hairs above

Silicle circular or suborbicular

Silicle ovate, rhomboid, oblong, or elliptic

Uppermost lvs pinnatifid; stem hairs spreading, 0.2-0.25 mm long

2. *bonariense

Uppermost lvs entire or toothed; stem hairs curved, < 0.1 mm long

Petals 0 or < sepals; silicle 2.5 × 2-2.5 mm

4. *densiflorum

Petals > sepals; silicle 2.5-3 × 2.8-3.2 mm

10. *virginicum

Stamens 6; petals > sepals; stem lvs with narrow pointed amplexicaul basal lobes

Stamens 2-(4); petals < sepals; stem lvs cuneate to auriculate at base, not amplexicaul

Silicle densely papillate; style not, or hardly, protruding beyond apical notch of silicle; anthers yellow

3. *campestre

Silicle not, or sparsely papillate; style protruding beyond apical notch of silicle; anthers red or violet

6. *heterophyllum

Silicle > 2.5 mm wide

12. flexicaule

Silicle < 2.5 mm wide

Lowest lvs toothed; silicle elliptic, glabrous

1. *africanum

Lowest lvs pinnatifid to pinnatisect; silicle rhomboid or ovate, glabrous or with sparse short straight hairs

Silicle ovate, 2.7-3 × 2-2.3 mm; upper lvs with small triangular cartilaginous marginal denticles often paired from a common base

5. *desvauxii

Silicle narrowly rhomboid, 2.7-3 × 1.8-2-(2.2) mm; upper lvs without denticles but sometimes with short stiff single marginal hairs

7. *hyssopifolium

Basal and lower stem lvs entire to toothed or crenate

Basal and lower stem lvs pinnatifid to pinnate

Basal lvs withering at fruiting; pedicel hairs tapering, in 1 row; stamens 2

Basal lvs persistent; pedicel usually glabrous, or rarely with sparse scattered pale clavate hairs; stamens 4-6

Stem ridged or grooved, at least when dry; silicle (2)-2.5-2.8 × 1.8-2 mm

1. *africanum

Stem smooth; silicle 3.3-3.5 × 2.2-2.5 mm

*divaricatum ζ

Stems filiform, prostrate; lvs entire, linear-spathulate to linear-oblanceolate

13. kirkii

Stems stout, decumbent to erect; lvs serrate, dentate or crenate

Silicle acute, not winged

15. oleraceum

Silicle notched, narrowly winged

Silicle cordate at base; lvs sharply toothed

11. banksii

Silicle abruptly tapered to base; lvs crenate to bluntly dentate

14. obtusatum

Petals > sepals

Petals < sepals

Stem glabrous; middle stem lvs pinnatifid; silicle 5-6 × 3-5 mm, elliptic; cotyledons 3-fid

9. *sativum

Upper stem hairy; middle stem lvs toothed; silicle 2.5-3 × 2.8-3.2 mm, almost circular; cotyledons simple

10. *virginicum

Infl. 1-3-(4) cm long, lf-opposed and overtopped by vegetative stem; silicle > 2.5 mm wide

12. flexicaule

Infl. (3)-5-10 cm long, terminal, not overtopped by vegetative stem; silicle < 2.5 mm wide

Basal lvs persistent at fruiting; stamens 4; flowering stems prostrate to ascending; silicle suborbicular, 1.5-2 × 1.5-1.8 mm

17. tenuicaule

Basal lvs withering at fruiting; stamens 2-(4); flowering stems erect to suberect; silicle ovate, 2.4-3.5 × 1.6-2.4 mm

Stem ridged or grooved; silicle 2.4-2.7 × 1.8-2 mm; pedicel hairs in 1 row

8. *pseudotasmanicum

Stem smooth; silicle c. 3.5 × 2.1-(2.4) mm; pedicel glabrous

*pseudohyssopifolium ζ

150 spp., cosmopolitan. Native spp. 7, naturalised 12.

Silicles of Lepidium vary a little in size and shape. For consistency, measurements of silicles should be made at about the middle of a fruiting raceme. Silicles of most spp. and the major stem hair types are shown in Fig. 45.

L. ruderale is not present in N.Z.; specimens of several other spp., including L. africanum, L. desvauxii, L. hyssopifolium, and L. pseudotasmanicum have been misidentified as L. ruderale in the past.

The whole genus was revised by Thellung, A., Neue Denkschr. Schweiz. Ges. Naturw. 41(1): 1-340 (1906). Australian spp. were revised by Hewson, H. J., Brunonia 4 : 217-308 (1981); Lepidium in Fl. Australia 8 (1982).

Fig. 45. Lepidium. A-Q silicles: A L. divaricatum; B L. densiflorum; C L. virginicum; D L. desvauxii; E L. kirkii; F L. sisymbrioides subsp. sisymbrioides; G L. campestre; H L. heterophyllum; I L. oleraceum; J L. africanum; K L. hyssopifolium; L L. pseudotasmanicum; M L. bonariense; N L. banksii; O L. tenuicaule; P L. flexicaule; Q L. sativum. R-T stems: R glabrous and ridged, S pubescent, T puberulent. © All rights reserved. [Image: 4X54]

Lepidium L.

Key

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