Aralia

1. Plant a large sparsely branched shrub or small tree with thick spiny stems to ca. 5 m tall.

2. Inflorescences as wide as tall or wider, central axis lacking or short; main veins (visible on the underside of the leaflets) extending into the leaf teeth; leaflets pubescent or with small spines beneath, at least on the veins. 

A. elata

2. Inflorescences much taller than wide, with a strong central axis; main veins (visible on the underside of the leaflets) anastomosing before the margins and not extending into the leaf teeth; leaflets glabrous beneath, except sometimes along the midrib.

A. spinosa

1. Plant herbaceous or with a short soft-wooded spiny base not more than ca. 1–3 (–5) dm tall.

3. Inflorescence a large spreading panicle of numerous small umbels, often axillary as well as terminal.

A. racemosa

3. Inflorescence of 3–13 umbels, terminal on erect peduncles (the umbels on spreading rays).

4. Plant with erect leafy stem prickly and often woody toward the base.

A. hispida

4. Plant essentially stemless, the petioles and peduncles arising from the base, not prickly.

A. nudicaulis

All species found in Aralia

Aralia elataANGELICA TREE 
Aralia hispidaBRISTLY SARSAPARILLA 
Aralia nudicaulisWILD SARSAPARILLA 
Aralia racemosaSPIKENARD 
Aralia spinosaHERCULES-CLUB, DEVIL’S WALKING-STICK, HERCULES-CLUB 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. August 18, 2017. http://michiganflora.net/genus.aspx?id=Aralia.