Key to Senna

View taxon page for Senna

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

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

1. Perennial herb to subshrub; leaflets generally 4–18

2. Leaflets 4–8; gland(s) on main 

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).

 axis between 

leaflet 

A leaf-like unit of a compound leaf; distinguished from a leaf by the absence in its axil of a bud, branch, thorn, or flower; lacking lateral, basal appendages (stipules); either simple (leaf 1-compound, with primary leaflets) or compound (leaf 2-compound, with primary and secondary leaflets; 3-compound, with primary, secondary, and tertiary leaflets, etc).

pairs; plant densely hairy ..... S. covesii

2' Leaflets 12–18; gland(s) near base of 

petiole 

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

; plant glabrous ..... [S. marilandica]

1' Shrub to small tree; leaflets generally 4–20

3. Shrubs of dry places; leaflets 

linear 

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

or generally 

ovate 

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

, generally flat, persistent or < 1 cm, ephemeral

4. Stem, leaf ± glabrous; leaflets 4–8, 4–6 mm ..... S. armata

4' Stem, leaf sparsely to densely hairy; leaflets 6–16, 10–25 mm ..... S. artemisioides

3' Shrubs to small trees generally not of dry places; leaflets 

oblong 

Longer than wide, with nearly parallel sides; wider than linear.

to 

elliptic 

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

, not ephemeral

5. Stipules 6–17 mm, ovate-cordate, generally persistent; uppermost, unopened flowers covered by bracts; fruit flat, 

dehiscent 

Opening at maturity to release contents; usually pertaining to anthers or fruits.

..... S. didymobotrya

5' Stipules 3.5–7 mm, 

lanceolate 

Narrowly elongate, widest in the basal half, often tapered to an acute tip.

, ephemeral; uppermost, unopened flowers not covered by bracts; fruit not flat, 

indehiscent 

Not opening inherently to release contents; usually pertaining to fruits.

..... S. multiglandulosa

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