Your help is appreciated. We depend on donations to help keep this site free and up to date for you. Can you please help us?

Donate

Native Plant Trust: Go Botany Discover thousands of New England plants

Rorippa aquatica — lake yellow-cress

Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.

New England distribution

Adapted from BONAP data

Found this plant? Take a photo and post a sighting.

North America distribution

Adapted from BONAP data

enlarge

Facts

Lake yellow-cress is at the edge of its range in New England. It is widely distributed outside New England, but is apparently rare throughout its range. Its habitat requirements include clear, slow-moving water with seasonal water level fluctuations, over calcareous bedrock. Invasive plants and eutrophication may be significant threats to the remaining New England populations.

Habitat

Lacustrine (in lakes or ponds), riverine (in rivers or streams)

Characteristics

Habitat
aquatic
New England state
  • Massachusetts
  • Vermont
Flower petal color
white
Leaf type
  • the leaves are compound (made up of two or more discrete leaflets
  • the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
Leaf arrangement
alternate: there is one leaf per node along the stem
Leaf blade edges
  • the edge of the leaf blade has lobes, or it has both teeth and lobes
  • the edge of the leaf blade has teeth
Flower symmetry
there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
Number of sepals, petals or tepals
there are four petals, sepals, or tepals in the flower
Fruit type (general)
the fruit is dry and splits open when ripe
Show all characteristics

  • Clonal plantlets

    Bulbils
    the plant does not appear to have bulbils
    Bulblets replace flowers
    there are no bulblets where the flowers are located

  • Flowers

    Anther opening
    the anthers have narrow slits or furrows that run lengthwise along the anthers
    Anther spurs
    the anthers do not have spurs on them
    Calyx symmetry
    there are two or more ways to evenly divide the calyx (the calyx is radially symmetrical)
    Carpels fused
    the carpels are fused to one another
    Cleistogamous flowers
    there are no cleistogamous flowers on the plan
    Corolla morphology
    NA
    Corolla palate
    no
    Corona lobe length
    0 mm
    Epicalyx
    the flower does not have an epicalyx
    Epicalyx number of parts
    0
    Filament surface
    the filament is smooth, with no hairs or scales
    Flower description
    the flower has a superior ovary, and lacks a hypanthium
    Flower petal color
    white
    Flower reproductive parts
    the flower has both pollen- and seed-producing parts
    Flower symmetry
    there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
    Flowers sunken into stem
    no
    Fused stamen clusters
    NA
    Horns in hoods (Asclepias)
    NA
    Hypanthium
    the flower does not have a hypanthium
    Inflorescence one-sided
    the flowers are arrayed in a spiral around the inflorescence axis or branches, or occur singly, or in several ranks
    Inner tepals (Rumex)
    NA
    Nectar spur
    the flower has no nectar spurs
    Number of pistils
    1
    Number of sepals, petals or tepals
    there are four petals, sepals, or tepals in the flower
    Number of styles
    0–1
    Ovary position
    the ovary is above the point of petal and/or sepal attachment
    Petal and sepal arrangement
    the flower includes two cycles of petal- or sepal-like structures
    Petal and sepal colors
    yellow
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal folds or pleats
    the petals of the flower do not have folds or plaits
    Petal hairs (Viola)
    NA
    Petal number
    Up to 4
    Petal tips (Cuscuta)
    NA
    Reproductive system
    all the flowers have both carpels and stamens (synoecious)
    Scales inside corolla
    no
    Sepal and petal color
    the sepals are different from the petals
    Sepal appendages
    the sepals do not have appendages on them
    Sepal appendages (Oenothera)
    NA
    Sepal number
    4
    Stamen attachment
    the stamens are not attached to the petals or tepals
    Staminodes
    there are no staminodes on the flower
    Umbel flower reproductive parts
    NA
    Upper lip of bilabiate corolla
    NA

  • Fruits or seeds

    Achene relative orientation
    NA
    Achene shape
    NA
    Achene surface (Polygonum)
    NA
    Achene type
    NA
    Berry color
    NA
    Capsule color (Viola)
    NA
    Capsule ribs
    NA
    Capsule splitting
    • NA
    • the capsule splits by two main valves, teeth or pores
    Fruit (pyxis) dehiscence
    NA
    Fruit features (Brassicaceae)
    NA
    Fruit locules
    two
    Fruit type (general)
    the fruit is dry and splits open when ripe
    Legumes (Fabaceae)
    NA
    Mericarp length
    0 mm
    Mericarp segment shape (Desmodium)
    NA
    Other markings on berry
    NA
    Ovary stipe
    the ovary or fruit does not have a stipe
    Placenta arrangement
    the plant has parietal placentation, where ovules develop on the wall or slight outgrowths of the wall forming broken partitions within a compound ovary
    Schizocarpic fruit compression
    NA
    Schizocarpic fruit segments
    0
    Septum in fruit (Brassicaceae)
    The fruit is either not compressed or is compressed parallel to the septum; therefore, the fruit and its septum are about the same width
    Wings on fruit
    the fruit does not have wings on it
    prickles on fruits
    the fruits do not have thorn-like defensive structures

  • Glands or sap

    Glands on leaf blade
    the leaf blades do not have glandular dots or scales
    Sap
    the sap is clear and watery
    Sap color
    the sap is clear

  • Growth form

    Parasitism
    the plant is not parasitic
    Plant color
    the leaves or young stems of the plant are green
    Plants darken when dry
    no
    Spines on plant
    the plant has no spines

  • Leaves

    Bracteole number (Apiaceae)
    0
    Bracts in plantain (Plantago)
    NA
    Leaf arrangement
    alternate: there is one leaf per node along the stem
    Leaf blade edges
    • the edge of the leaf blade has lobes, or it has both teeth and lobes
    • the edge of the leaf blade has teeth
    Leaf blade surface colors
    the upper side of the leaf blade is relatively uniform in color
    Leaf form
    the leaves are green, with an expanded blade and a leaf-like texture
    Leaf spines
    there are no spines on the leaf edges
    Leaf teeth and lobes
    • the leaf blade margin has forward-pointing teeth
    • the leaf blade margin has rounded teeth
    • the leaf has a row of two or more lobes on each side of the central axis
    Leaf type
    • the leaves are compound (made up of two or more discrete leaflets
    • the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaves per node
    there is one leaf per node along the stem
    Specific leaf type
    • the leaf has a row of two or more lobes on each side of the central axis
    • the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Stipule features
    NA
    Stipules
    there are no stipules on the plant

  • Place

    Habitat
    aquatic
    New England state
    • Massachusetts
    • Vermont
    Specific habitat
    • in lakes or ponds
    • in rivers or streams

  • Stem, shoot, branch

    Branched tendrils
    NA
    Flowering stem cross-section
    the flowering stem is circular, or with lots of small angles so that it is roughly circular
    Hooked hairs on stem between nodes
    no
    Leaves on stem
    there is at least one full leaf above the base of the flowering stem
    Tendril origin
    NA
    Tendrils
    the plant does not have tendrils

Wetland status

Occurs only in wetlands. (Wetland indicator code: OBL)

New England distribution and conservation status

Distribution

Connecticut
absent
Maine
absent
Massachusetts
present
New Hampshire
absent
Rhode Island
absent
Vermont
present

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

Maine
historical (S-rank: SH), potentially extirpated (code: PE)
Massachusetts
unranked (S-rank: SNR)
Vermont
extremely rare (S-rank: S1), threatened (code: T)

Native to North America?

Yes

Sometimes confused with

Nasturtium officinale:
fruits mostly 10-18 mm long, anthers 0.6-1 mm long, and leaves once pinnately compound (vs. R. aquatica, with fruits 4-7 mm long, anthers 1.7-2.2 mm long, and leaves variable, the submergent ones pectinate into narrow segments, the emergent ones simple and toothed or lobed).
Nasturtium microphyllum:
fruits mostly 14-22 mm long, anthers 0.7-1 mm long, and leaves once pinnately compound (vs. R. aquatica, with fruits 4-7 mm long, anthers 1.7-2.2 mm long, and leaves variable, the submergent ones pectinate into narrow segments, the emergent ones simple and toothed or lobed).

Synonyms

  • Armoracia aquatica (Eat.) Wieg.
  • Armoracia lacustris (Gray) Al-Shehbaz & Bates
  • Nasturtium lacustre Gray
  • Neobeckia aquatica (Eat.) Greene
  • Rorippa americana (Gray) Britt.

Family

Brassicaceae

Genus

Rorippa

Help

From the dichotomous key of Flora Novae Angliae

2. Rorippa aquatica (Eat.) Palmer & Steyermark NC

lake yellow-cress. Armoracia aquatica (Eat.) Wieg.; A. lacustris (Gray) Al-Shehbaz & Bates; Nasturtium lacustre Gray; Neobeckia aquatica (Eat.) Greene; Rorippa americana (Gray) Britt. 
• MA, VT; western portion of states; also reported from ME by Campbell et al. (1995), but specimens are unknown. Lakes and slow-moving rivers in high-pH bedrock regions.