Montana Field Guide

PLANTS: Perennial aquatic herbs with submerged stems, bladders, and overwintering buds. Plants are rootless with slender stems. Bladders, which trap algae and small aquatic animals for the plants nourishment, are borne on leafy, submerged branches. Source: Lesica et al. 2012.

LEAVES: The leaves are mostly 2-8 mm long, palmately divided, with flat and entire segments. Source: Lesica et al. 2012.

INFLORESCENCE: An erect, few flowered, bracteate raceme. 2 to 5 flowers are emergent, yellow, and snapdragon-like. Source: Lesica et al. 2012.

The specific epithet minor refers to this species’ smaller size compared to others within the genus. Utricularia is derived from the Latin utriculus which translates to wineskin or leather bottle referring to the sac-like bladders of the genus (Poppinga et al. 2016).

Flowering May through September (Neid 2006).

Montana has four Utricularia species. They are all aquatic, submerged, rootless herbs with small bladder-like traps borne on branches or leaves. All species have emergent, snapdragon-like flowers borne on a scape. All have many, globose overwintering buds called turions.

Lesser Bladderwort – Utricularia minor, native and desirable
*Size: Scape emerges 5-10 cm from the water.
*Bladders: 1-3 mm long and occur only on leafy stems.
*Bladder Glands: Long arm-pair diverging slightly. Short arm-pair diverging by 270–300 degrees (so all 4 arms oriented in the same direction) (Rice 2012).
*Leaves: 2-8 mm long and palmately divided. Segments are flat with entire margins.
*Buds: 2-9 mm long.
*Flowers: 2-5 yellow flowers in an inflorescence. Each is 5-10 mm long with a 2 mm long spur.
*Fruit: Borne on curved pedicels when mature.

Flatleaf Bladderwort – Utricularia intermedia, native, SOC
*Size: Scape emerges 8-25 cm from the water.
*Bladders: 3-5 mm long and borne on separate leafless branches.
*Bladder Glands: Both arm-pairs generally diverge by 0–30 degrees (Rice 2012).
*Leaves: 5-20 mm long, palmately divided. Segments are flat with entire to obscurely serrate margins.
*Buds: 6-15 mm long.
*Flowers: 1-4 yellow flowers in the inflorescence. Each is 10-15 mm long with a 5-9 mm long spur.
*Fruit: Borne on erect pedicels when mature.

Greater Bladderwort – Utricularia vulgaris, native and desirable
*Size: Scape emerges 10-40 cm from the water.
*Bladders: 2-5 mm long and only attached to leaf segments.
*Bladder Glands: Long arm-pair is parallel or diverges slightly. Short arm-pair diverges by 90–180 degrees (Rice 2012).
*Leaves: Pinnately divided and crowded. 20-50 mm long, entire and more or less round.
*Buds: 15-25 mm long.
*Flowers: More than 5 yellow flowers in the inflorescence. Each is 10-18 mm long with a 5-8 mm long spur.
*Fruit: Borne on curved pedicels when mature.

Northern Bladderwort – Utricularia ochroleuca, native, SOC
*Size: Scape emerges up to 15 cm from the water
*Bladders: Most are borne on leafless stems but a few can often be found on leafy shoots.
*Bladder Glands: long arm-pair diverging by 20–45°, short arm-pair diverging by 40–160 degrees (Rice 2012)
*Leaves: 5-15 mm long and palmately divided. Terminal leaf segments with bristle tips and toothed margins.
*Buds: 2-3 mm and bristly
*Flowers: Inflorescence usually 3-5 flowered. Each is 8-11 mm long with a 10-15 mm long spur.
*Fruit: Borne on curved pedicels when mature.

Shallow water of fens, fen lakes, ponds; valleys, montane (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Utricularia ochroleuca is most likely a hybrid of U. minor x U. intermedia (Rice 2012).

BLADDER FUNCTION
All Bladderwort species are carnivorous plants that use small bladder-like traps to capture and digest prey. Prey includes aquatic insect larvae, water mites, nematodes, gastropods, small tadpoles, crustaceans, diatoms, and other aquatic microorganisms (Mette et al. 2000). Each trap has a valve that opens like a trap door when the surrounding trigger hairs are brushed (Poppinga et al. 2016). When the valve opens, a low pressure gradient causes water to flow quickly inside pulling in the organism that triggered the hairs (Singh et al. 2011). Glands found on the inside of the traps both digest prey through enzyme excretion, and absorb the nutrients after digestion (Poppinga et al. 2016).

UTRICULARIA AND ALGAE
While Utricularia are considered “carnivorous” plants, their nutrient acquisition is much more complicated than carnivory alone. In fact, algae have been observed inside bladders more often than anything else (Plachno et al. 2012). This has caused a close and complex relationship to develop between Utricularia species and algae. Individuals trap and digest algae for nutrients, and also host algae and other microorganisms that live within traps, creating an elaborate food-web community (Peroutka et al. 2008; Ellwood et al. 2018). Fungi, bacteria, and protozoa are cultivated within traps and help to break down algae into a state that can be digested by the bladderwort (Sirová et al. 2018).

According to a study by Ulanowicz (1995), Utricularia species use a positive feedback loop in order to survive in an oligotrophic environment in which other aquatic plant species would be nutrient stressed. By acting as a physical structure for periphyton to grow on, they attract the organisms that graze on periphyton which they will then feed upon (Ulanowicz 1995).

PHOTOSYNTHESIS AND RESPIRATION
In addition to preying on a wide variety of other organisms, bladderworts photosynthesize in order to obtain energy. Adamec (2005) showed that the photosynthetic rate of leaves was much higher than that of bladders whereas respiration of bladders was much higher than that of the leaves. This implies that while bladders obtain essential nitrogen and phosphorous from digesting prey, function of these structures necessitates high metabolic costs (Adamec 2005). While the benefits of carnivory in Utricularia are not fully understood, this investment of energy suggests some net advantage to trap operation.</u.></u.>

FLOWERS [Lesica et al. 2012; Hitchcock and Cronquist 2018]
Emergent flowers have an inconspicuous, two-lobed calyx and a dull yellow, two-lipped corolla. The corolla is usually 5-10 mm long. Underneath, it has a spur, which is about 2 mm long; above, it has a small to obsolete palate. The upper corolla lip is less than half the length of the lower lip.

FRUIT
The fruit is a circumscissile capsule 1 mm long or less that is borne on a curved pedicel (Lesica et al. 2012; Rice 2012)

LIFE CYCLE [Adamec 1999]
U. minor is a perennial species. Its turions begin forming in late August and are surrounded by a matrix of branched leaves. By late September and early October, branches die and drag the turions to the bottom. In late autumn, the turions break free but remain submerged and tangled in the branches. Once the branches fully decompose, the turions float to the surface and begin new growth in the spring.

Conservation impacts on Utricularia minor are essentially unstudied, but populations are known to be particularly sensitive to changes in water quality. Efforts to maintain and improve water quality and preserve suitable habitat should therefore be taken to sustain populations. This may include monitoring hydrologic impacts on watersheds where Utricularia minor is found, and establishing buffers around identified locations. Source: Neid 2006.

As nutrient levels rise in oligotrophic habitats, periphyton and algae growth will begin to choke-out Utricularia plants, at which point they no longer benefit from attracting algae (Ulanowicz 1994). In this situation, algae-suppressive treatments are harmful to bladderworts that are caught amongst the algae. Introducing Daphnia and tadpoles is the only known method of suppressing algae that does not harm Utricularia. Source: Carnivorous Plant Resource.

Invasive species, habitat loss and hydrologic alterations are the main threats to Utricularia minor. This species is very sensitive to changes in water quality so land use practices that have a high impact on both local and landscape scale habitat integrity also threaten populations. Furthermore, fens, which are the primary habitat of Lesser Bladderwort, are both restricted in range and sensitive to environmental change. Source: Neid 2006.

While a certain level of nutrients can attract a beneficial amount of algae and periphyton, very high nutrient levels resulting in unchecked growth of algae can displace Utricularia populations (Ulanowicz 1994).