aquatic plants identification guide 2012 - Invasive Species … Bownes Papers... · Field Identification guide Invasive aquatic plants Categorized, ... Azolla filiculoides 1 Red water

Field Identification guide

Invasive aquatic plants Categorized, new and

similar indigenous species

Compiled by:

Debbie Sharp

DEA: EP

Key to identification guide

Category under CARA (red=proposed)

Established plant

Categorised under CARA

New, emerging species

Chemical control methods available

Biological control available

No known control methods available

Minor use and best practice in process

(Categorised under Conservation of Agricultural Resources Act , 1947)

Minor use applications under Act 36 for herbicide applications on new/emerging species.

1, 2, 3

D. S

harp

D

. Sha

rp

Arundo donax

Giant Spanish reed, Reuse Spaanseriet

1

Forms dense stands, large, robust, 2-6m tall, Spear-shaped compact inflorescence, perennial , grass-like , leaf tips soft and not firm –like indigenous reed, Phragmites mauritianus. Invades watercourses and dry land.

Mature plants on riverbank

Inflorescence

P. mauritianus

D. S

harp

D

. Sha

rp

D. S

harp

Pontederia cordata

Pickerelweed, Jongsnoekkruid

3

Perennial, rooted aquatic, 1-2m high, forms horizontal rhizomes and erect emergent stems. Leaves light green and arrow shaped. Flowers blue, September – June. Propagates vegetatively. CARA category 3

Flower spike

Mature plant

Plant showing arrow-like leaves

D. S

harp

D

. Sha

rp D. S

harp

Eichhornia crassipes

Water hyacinth, Waterhiasint

3

Free-floating, perrenial aquatic plant. Sometimes rooted in shallow water. Forms dense mats, propagates vegetatively and from seed, flowers pale blue to violet in 8-10 spikes, each flower 50mm in diameter. Upper petal dark blue, with yellow centre. November – April, flowers continuously. Found in dams and slow flowing rivers. Successful biocontrol and chemical control. CARA category 1.

Large infestation, Roodeplaat dam

CL. S

harp

Mature plant

D. S

harp

J. Co

etze

e

Pistia stratiotes

Water lettuce, Waterslaai

1

Perennial, mat forming, floating aquatic and propagates vegetatively and from seed. Plant has rosette of leaves resembling an open cabbage. Leaves hairy, pale green with prominent longitudinal veins. Invades dams, rivers and streams in tropical areas. Flowers all year, but inconspicuous. Intense internal irritation caused when ingested. Category 1 under CARA. Successful biocontrol agent available

Infestation on Berg River

Large infestation

CL. S

harp

CJ

Cill

iers

J. Co

etze

e

1

Dense, mat-forming floating aquatic fern. Leaves are yellow to green, oval and in pairs. Leaves are waterproof and velvety, dense hairs end in cage-like structures that trap bubbles, Modified, featherlike roots. Invades slow-moving water and dams in frost-free regions. Propagates vegetatively only. Category 1 under CARA, successful biocontrol available and chemical control not necessary.

Salvinia molesta

Kariba weed, Watervaring

Mature plant showing leaves and roots

Cage-like hair structures

Kariba weed infestation

Salvinia minima

Small salvinia

CJ C

illie

rs

CJ C

illie

rs

L. H

ende

rson

Dense mat-forming floating aquatic fern with oval, green leaves in whorls of three. Leaves are small, 8mm wide, waterproof and velvety, dense hairs end in four fingers, free at the tip. Modified, featherlike roots. Invades slow-moving water and dams in frost-free regions. Propagates vegetatively only. Not categorized under CARA, new species.

1 Myriophyllum aquaticum

Parrots feather, Waterduisendblaar

Mature plant showing leaves

Lysathia sp. feeding damage

Parrots feather infestation forming dense mats D. S

harp

D. S

harp

D. S

harp

Rooted, aquatic plant with terminal, leafy shoots emerging above water surface. Roots arise at stem nodes. Leaves green, finely divided, feather-like, arranged in whorls of 4-6. Flowers cream, inconspicuous, only female plants in SA. Category 1 in CARA. Successful biocontrol and chemical control available.

1 Azolla filiculoides

Red water fern, Rooiwatervaring

CJ C

illie

rs

CJ C

illie

rs

CJ C

illie

rs

Perennial, mat-forming , aquatic fern, appearing circular in outline and not pyramidal like the indigenous A. pinnata. Root tips often coiled. Leaves silvery-green, turning reddish, brown or purplish in winter. Leaves ovate to almost circular. Minute fruiting bodies in axis of leaves. October – February. Category 1 under CARA, Successful biocontrol available, chemical control not necessary

Large Infestation

Adult plants

Adult plants

J. Co

etze

e

J. Co

etze

e

Perennial, mat-forming, floating aquatic fern similar to A. filiculoides but smaller and roots with conspicuous root caps. Prefers tropical areas such as lowveld of Mpumalanga, Limpopo and coastal KZN. Proposed category 1 under CARA and NEMBA. Potential successful biocontrol

1 Azolla microphylla

Tropical red water fern, Tropiese rooiwatervaring

J. Co

etze

e

Adult plants close up

A microphylla mat

Large Infestation

This Azolla species is also invasive in South Africa but has only been found in KZN to date. Proposed category 1 under CARA and NEMBA.

1 Azolla pinnata asiatica

Mosquito fern

Adult plants close up

Infestation, Tinley manor, KZN

J. Co

etze

e

J. Co

etze

e

Nymphaea mexicana

Yellow water lily, Geelwaterlelie

NV

Kroo

n

Floating plants with yellow flower Rooted, perennial floating aquatic macrophyte. Flowers bright yellow fragrant, with pointed petals, cultivars have pale yellow flowers with more rounded petals. Upper surface of leaves green with brown blotches. Rhizomes, vertical, stout and knobbly, connected with horizontal stolons. Pale, long spongy roots anchor mass. Invades riverbanks and dam edges. Reproduction by vegetative stolons. Proposed category 1 under CARA and NEMBA. Not to be confused with indigenous spp – Nymphoides thunbergiana, Nymphaea capensis, and N. nouchali.

1

Flowers showing dense spikes

Rooted, perennial aquatic weed. Flowers are purple in dense spikes. Emerging species with minor use registrations. Limited populations currently, in Liesbeeck River in Cape Town. Highly aggressive and has potential to invade other systems. Declared category 1 under CARA

Lythrum salicaria

Purple loosestrife

Mature plants

Flowers

Plant showing leaves

E. v

an W

yk

E. v

an W

yk

E. v

an W

yk

J. Co

etze

e

1

Sagittaria platyphylla

Delta arrow weed

1

H. S

itho

le

H. S

itho

le

H. S

itho

le

Perennial aquatic herb up to 1.5m tall with creeping stolons. Submerged leaves narrow, strap-like, emergent leaves wider, pointed and abruptly narrowed into triangular petiole. Upright flowering stems. 2-12 whorls, white 3-petalled male flowers above small, green, petalless female flowers. Propagates by seed, creeping stolons, corms, entire floating plants. Proposed category 1 under CARA and NEMBA.

Flowers

Mature plant

Rooted plants

J. Co

etze

e

Rooted, submerged aquatic plant, except for leafless flowering shoots. Propagates vegetatively and from seeds, stems are up to 3m long with few and small roots but forms dense impenetrable mats. Leaves are olive green, finely divided and arranged in whorls of 4-6. Flowers cream, small, female and male, arranged in whorls on emergent spikes 100mm long. Fruits are small nuts. Category 1 under CARA. Registered herbicides but currently no biocontrol. Mature plant showing fine whorled leaves

Mature plant showing flower bud

Spiked water milfoil mat

Mat easily identified by algae on water’s surface

Myriophyllum spicatum

Spiked water-milfoil

1

J. Co

etze

e

J. Co

etze

e

Raym

ond

New

man

Flower

Rooted, submerged, perennial aquatic weed. Branching stems 2m or longer. Leaves are mainly submerged, fan-like opposite/in whorls. Few floating leaves, usually associated with flowering. Solitary white/pinkish flowers, emergent, 3-petalled. Not to be confused with Ceratophyllum demersum that has toothed leaf margins & inconspicuous flowers in leaf axils. Invades rivers lakes and dams. Proposed category 1 under CARA and NEMBA. Ornamental pond plant. Not recorded as established in SA.

Cabomba caroliniana

Fanwort, Cabomba

J. Co

etze

e

J. Co

etze

e

J. Co

etze

e

Mature plant

C. caroliniana mat

1

Submerged, rooted aquatic plant with slender stems in excess of 3m. Leaves green, finely serrated, 15mm long usually in whorls of 3, rarely 4. Cream to yellow flowers, 3 petals on long threadlike stalks that float. Invades lakes, ponds and rivers. Category 1 under CARA. Ornamental in aquarium trade. Chemical control available, but no biocontrol. Not recorded as established in SA.

CJ C

illie

rs

Dan

Min

chin

Elodea canadensis

Canadian waterweed, Kanadese waterpes

1

Mature plant

Plant showing leaves in whorls of three

Submerged, rooted aquatic weed, can fragment, fragments survive in free-floating mats. Leaves are 2-4mm wide, 6-20mm long, in whorls of 3-8. Leaf margins distinctly serrated, midrib often red. Current research on chemical and biocontrol. Proposed category 1 under CARA and NEMBA

Hydrilla verticillata

Hydrilla

Plant showing leaves in whorls of six

Vegetative propagule

Hydrilla mass

Hydrilla infestation

J. Co

etze

e

D. S

harp

D

. Sha

rp

A.B

owne

s

1

Persicaria amphibia

Water knotweed

D. S

harp

D. S

harp

D. S

harp

Rooted perennial aquatic weed with thick stems arising from rhizomes. Stems creep, grow erect or float and root at nodes and up to 3m long. Lance-shaped leaves borne on petioles. Inflorescence dense terminal clusters of many 5-lobed pink flowers

Flowers

Knotweed infestation, Mearns weir

Mature plant

Valisneria spiralis

Tape grass, Eelgrass

Submerged, rooted aquatic weed with rosettes of long strap-like leaves up to 5m, arising from base. Stout rhizomes with numerous roots up to 40cm long. Male flowers free floating with female flowers on spiral peduncle. Current research on chemical control

Mature plant

Female flower, closed and open

Tape grass mat Female spiral peduncle and juvenile plant and

D. S

harp

D. S

harp

D. S

harp

Flor

idaa

quat

ic.c

om

INDIGENOUS SPECIES NOT TO BE CONFUSED WITH INVASIVES

Ceratophyllum demersum

D. S

harp

D. S

harp

Wor

king

for

wat

er


Lagarosiphon major

Cape

l.ver

ygrr

een.

co.u

k

Luir

ig.a

lter

vist

a.or

g


Lagarosiphon verticilifolia

L. H

ende

rson

L. H

ende

rson

L. H

ende

rson


Ludwigia stolonifera

D. S

harp

Fl

eurs

.cir

ad.fr

Zim

babw

eflo

ra.c

o.zw

Nymphoides thunbergiana


D. S

harp

D. S

harp

D. S

harp


Potamogeton crispus

Biol

ib.c

z

Bota

ny.c

z

wik

iped

ia


Aponogeton distachyos

D. S

harp

D. S

harp

D. S

harp


Potamogeton pectinatus

wik

iped

ia

Biop

ix.e

u


Phragmites mauritianus

D. S

harp

D. S

harp

D. S

harp


Potamogeton schweinfurthii

D. S

harp

D. S

harp

References

Henderson, L. and Cilliers, C.J. 2004. Invasive Aquatic Plants. A guide to the identification of the most important and potentially dangerous invasive aquatic plants in South Africa. PPRI handbook no. 16

Henderson, L. 2010. SAPIA news no. 15

Henderson, L. 2010. SAPIA news no.17

Henderson, L. 2012. SAPIA News No. 24

www.realtech.co.za/realwiki.php. The resource Library, Persicaria amphibia

Information compiled by D. Sharp with assistance from L. Henderson, J. Coetzee and A. Bownes.

aquatic plants identification guide 2012 - Invasive Species … Bownes Papers... · Field Identification guide Invasive aquatic plants Categorized, ... Azolla filiculoides 1 Red water

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