Key to Micranthes

View taxon page for Micranthes

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

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

1. Leaves cauline on ± trailing stem – 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

 

entire 

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

; flowers in head-like cluster ..... M. tolmiei

1' Leaves 

basal 

At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary.

(bracts occasionally leaf-like)

2. Proximal flowers replaced by 

bulblets 

1. Small bulb generally produced at the base of a bulb. 2. Any small, bulb-like structure that propagates a plant, often in a leaf or bract axil.

; flowers ± 

bilateral 

Divisible into mirror-image halves in only one way.

, 3 petals broader than other 2

3. Base of all petals ± 2-spotted; 

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).

blade linear-elliptic, margin ± entire or with minute teeth distally ..... M. bryophora

3' Base of only 3 broad petals (rarely all) ± 2-spotted; leaf blade obovate, teeth generally coarse ..... M. ferruginea

2' Inflorescence bulblets 0; flowers 

radial 

Divisible into mirror-image halves in three or more ways.

, petals ± equal

4. Filaments inflated distally; petal spots 2

5. Leaf blade 

ovate 

Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf.

to 

elliptic 

In the shape of a flattened circle or ellipse; wider than linear

, base 

truncate 

Abruptly (not gradually) narrower or smaller at base or tip, as if cut straight across or nearly so.

to 

tapered 

Gradually (not abruptly) narrower or smaller at base or tip.

; ovaries fused only at base ..... M. marshallii

5' Leaf blade ± round, base 

cordate 

Heart-shaped; often pertaining to a leaf in which the blade base on both sides of the petiole is rounded and convex.

to 

reniform 

Kidney-shaped; often pertaining to a leaf in which the blade base on both sides of the petiole is rounded and concave.

; ovaries fused throughout – fruit tip purple, base yellow-banded ..... M. odontoloma

4' Filaments inflated proximally, or ± flat and not inflated; petal spots 0

6. Filaments inflated proximally; ovary superior in flower and fruit ..... M. howellii

6' Filaments not inflated proximally, ± flat, narrowed at tip; ovary ± inferior to 1/2-inferior in flower, superior in fruit

7. Plant generally > 4 dm; leaf blade 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

to oblanceolate, generally > 10 cm, long-tapered to an indistinct 

petiole 

Leaf stalk, connecting leaf blade to stem; sometimes more or less indistinct.

; bogs, marshes, lake margins ..... M. oregana

7' Plant <= 3.5 dm; leaf blade elliptic, obovate, ovate, or triangular, generally < 10 cm, short-tapered to a distinct petiole; not in bogs, marshes or lake margins

8. Leaf blade shallowly toothed; inflorescence ± open, often 1-sided; flowers not clustered to loosely clustered; anthers purple to red (orange); petals ± 2 × sepals; styles on fruit generally > 1.5 mm ..... M. californica

8' Leaf blade ± entire to minutely toothed; inflorescence not 1-sided; flowers loosely to densely clustered; anthers generally yellow to orange; petals < 1.7 × sepals; styles on fruit generally < 1 mm

9. Petals 1–2 mm; sepals ± 

reflexed 

Abruptly bent or curved downward or backward.

..... M. nidifica

9' Petals generally > 2 mm; sepals generally ± 

erect 

Upright; vertically oriented.

to 

spreading 

Oriented more or less perpendicularly to the axis of attachment; often, more or less horizontal.

(except Micranthes fragosa)

10. Pedicels ± glabrous to sparsely glandular; generally 1 head-like cluster of flowers at tip of inflorescence, sometimes with 1 or 2 smaller clusters on nearby short lateral branches; moist, sandy and gravelly montane to subalpine habitats >= 1600 m elevation ..... M. aprica

10' Pedicels densely glandular; lateral branches of inflorescence many, each with a terminal cluster of flowers; moist meadows, rocky slopes and outcrops

11. Lateral branches of inflorescence spreading to 

ascending 

Curving or angling upward from base, or about 30-60 degrees less than vertical or away from axis of attachment.

; inflorescence cluster at tip of main axis open to ± congested, hemispheric to ± flat-topped; sepals ± reflexed to spreading ..... M. fragosa

11' Lateral branches of inflorescence ascending to erect; inflorescence cluster at tip of main axis dense, conical to 

cylindric 

Elongate, with parallel sides and, at any point, round in transverse section.

; sepals ± erect to ascending ..... M. integrifolia

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