Key to Utricularia

View taxon page for Utricularia

(For a list of species in Utricularia, use the above link.)

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

1. Leaves 

simple 

Composed of a single part; undivided; unbranched.

, flattened; stolons subterranean; cleistogamous flowers common; bracts 

peltate 

With the stalk attached toward the middle, not at a margin, of a flat structure such as an indusium, scale, or leaf.

..... U. subulata

1' Leaves dissected into 2–many thread-like to flattened ultimate segments; stolons free-floating, loosely rooted, or subterranean; cleistogamous flowers rare; bracts attached at base

2. Stems generally of 1 kind (sometimes weakly of 2 kinds in Utricularia minor), with bladders, leaves throughout

3. Leaf 15–90 mm, ultimate segments > 30, margin bristles 0.1–0.3 mm; stem 30–150 cm; 

peduncle 

Stalk of an individual flower borne singly, not in an inflorescence, or of an entire inflorescence, or the corresponding structure in fruit; the stalk subtending an involucre (e.g., in Asteraceae, Polygonaceae).

1–3 mm diam; bladder glands with long arm-pair parallel or diverging slightly, short arm-pair diverging by 90–180° ..... U. macrorhiza

3' Leaf 2–15 mm, ultimate segments 2–22, margin bristles 0 or microscopic; stem 5–30 cm; peduncle 0.4–0.8 mm diam; bladder glands with long arm-pair diverging slightly, short arm-pair diverging slightly or by 270–300°

4. Ultimate 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

segments 2–6(8); corolla upper lip >= lower, spur ± = lower; bladder glands with both arm-pairs diverging slightly ..... U. gibba

4' Ultimate leaf segments 7–22; corolla upper lip, spur both <= 1/2 × lower lip; bladder glands with long arm-pair diverging slightly, short arm-pair diverging by 270–300° (so all 4 arms oriented in same direction) ..... U. minor (2)

2' Stems clearly of 2 kinds, green (in water or at surface; leaves with flattened or thread-like segments; bladders 0–few) and white (generally buried in substrate; leaves 0; bladders many)

5. Ultimate leaf segment margins without bristles; leaf segments ± thread-like to flattened; corolla 6–8 mm; bladder glands with long arm-pair diverging slightly, short arm-pair diverging by 270–300° (so all 4 arms oriented in same direction) ..... U. minor (2)

5' Ultimate leaf segment margins with bristles 2–12, 0.08–0.16 mm; leaf segments flattened; corolla 1–1.6 cm; bladder glands with long arm-pair diverging by 0–45°, short arm-pair diverging by 0–160°

6. Ultimate leaf segment margins with 5–12(20) bristles, ± 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

; leaf segment tips 

obtuse 

Having a short-tapered, blunt tip or base, the sides convex or straight and converging at more than a right angle.

; bladders on leafless shoots, rarely on leafy shoots; corolla spur < or ± = lower lip; bladder glands with both arm-pairs diverging by generally 0–30° ..... U. intermedia

6' Ultimate leaf segments margins with 1 bristle on each of 2–7(10) teeth; leaf segment tips 

acute 

Having a short-tapered, sharp tip, the sides convex or straight and converging at less than a right angle.

; bladders on leafless shoots, also often ± few on leafy shoots; corolla spur ± 1/2 × lower lip; bladder glands long arm-pair diverging by 20–45°, short arm-pair diverging by 40–160° ..... U. ochroleuca

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