Araceae . . . . . . Arum family
Also includes former Lemnaceae
Flowers:
Acorus
Arum
Zantedeschia
Lysichiton
Small floating plants:
Wolffia
Lemna
Lemna
Spirodela
Acorus . . . . . Sweet-flag
Acorus calamus . . . Sweet-flag
A plant of pond edges:
Arum . . . . . Arum
Arum italicum . . . . Italian Lords-and-Ladies
Similar to A. maculatum though A. italicum usually has pale leaf midrib and top of spadix yellow not purple; commonest in CI and near S coast and SE Ire, becoming more scattered in N En
Arum italicum subsp. italicum . . . . Italian Lords-and-Ladies (subsp. italicum)
Characteristic white veins and top of spadix yellow; commonest in CI and SW but can persist further N as garden thow-out
Arum maculatum . . . . . Lords-and-Ladies
Has purple spadix and no pale veins in leaf which often has a dark spot; the commoner sp. occurring everywhere in BI exc. NW Sc
Lysichiton . . . Skunk-cabbage
Lysichiton americanus . . . . American Skunk-cabbage
Garden escape growing particularly in damp areas, can be invasive
Zantedeschia . . . Arum Lily
Zantedeschia aethiopicus . . . Arum Lily
Garden escape growing particularly in damp areas
Arisarum . . . Friar's cowl, Mousetail
Arisarum proboscidium . . . Mousetail plant
A garden throw-out scattered in C Sc, S En, Ir and CI
Arisarum vulgare . . . Friar's-cowl
A similar Mediterranean plant, rarely encountered as a garden escape
Former Lemnaceae . . . . Duckweeds
Former Lemnaceae:
Wolffia
Lemna
Lemna
Spirodela
No roots
1-root
1-root
3+-roots
Lemna . . . . . Duckweed
Lemna have clear single roots attached to each frond
Lemna gibba . . . . . Fat Duckweed
In ponds/ditches esp. C & E En, uncommon in Sc & Ire; fronds hemispherical (Pic: Christian Fischer)
Lemna minor . . . . . Common Duckweed
Common throughout BI on ponds; adult fronds >2mm, flat on both surfaces with 3 faint ridges (veins) on u. surface
Lemna minuta . . . . . Least Duckweed
Fronds <2mm long; frequent in still water in En, Wa, Ire; local in Sc
Lemna trisulca . . . . . Ivy-leaved Duckweed
Frequent in still to flowing water in lowlands esp. in S Br and in C Sc; largely submerged
An unusual introduced sp. of S Br is L. turionifera (Red Duckweed); often red undersides
Spirodela . . . . . Greater Duckweed
Spirodela polyrhiza . . . . . Greater Duckweed
Larger, Fronds c.10 mm, >5 roots on each frond, rather local in Ire and mostly in S Br
Wolffia . . . . . Rootless Duckweed
Wolffia arrhiza . . . . . Rootless Duckweed
Rootless duckweed is tiny (c.1 mm), has no roots and is local in SE En and around Severn estuary
