i6 



MINNESOTA TREES AND SHRUBS 



into 



n. Shrubs 



(m) Bark many-layered, splitting 



shreds 

 (n) Bark firm 



r. Tall shrub with thorns 

 s. Bushes, sometimes prickly 

 (r) Leaves \-2 l /t dm. broad 

 (s) Leaves 1-10 cm. broad 

 h. Leaves broad, deeply lobed 

 i. Leaves longer than broad, 

 slightly lobed 

 (2) Leaves compound 



(a) Leaves pinnate 

 x. Leaves opposite 



(x) Vines 

 (y) Shrubs 

 y. Leaves alternate 



(x) Leaf margin entire 

 m. Leaves odd-pinnate 



(m) Tall spiny shrub with aromatic 



leaves 

 (n) Low bristly shrub ; leaves not aro- 

 matic 

 (o) Neither spiny nor aromatic 

 r. Leaflets over 5 cm. long 

 s Leaflets 5 cm. or less 

 (r) Leaflets 5-7 

 (s) Leaflets 11-49 

 n. Leaves even-pinnate 

 (y) Leaf margin toothed 

 m. Leaflets 3-5 



(m) Low small shrub or tall vine; leaf- 

 lets obscurely toothed or some- 

 times lobed 

 (n) Spiny bushes; leaflets coarsely 



toothed 

 (o) Smooth shrubs ; leaves finely serrate 

 n. Leaflets 5-many 



(m) Bushes or vines, usually prickly 

 (n) Shrubs 

 r. Sap milky 

 s. Sap clear 



(r) Tall native shrub 

 (s) Low cultivated shrub 



(b) Leaves palmate 

 x. Vines with tendrils 

 y. Bushes 



Physocarpus: ninebark 127 



Crataegus: hawthorn 154 



Rubus: raspberry 121 



Ribes : currant, gooseberry 185 



Spiraea: spiraea 128 



Clematis : clematis 46 



Sambucus : elderberry 278 



Xanthoxylum : prickly ash 80 



Robinia: rose acacia 175 



Rhus : poison sumac 227 



Potentilla: potentilla 119 



Amorpha: amorpha 177 



Caragana : pea tree 1 79 



Rhus : poison ivy 227 



Rubus: raspberry, blackberry 121 

 Staphylea: bladder nut 215 



Rosa : rose 134 



Rhus : sumac 227 



Sorbus : mountain ash 147 



Sorbaria: ash-leaved spiraea 132 



Parthenocissus : woodbine 203 



Rubus: blackberry 121 



Flower Key to Families 



I. Petals present 



1. Flowers single or in clusters 

 a. Petals separate 



(1) Petals 3, sepals 3, stamens and pistils in differ- 



ent flowers Smilacaceae 



(2) Petals 4 



(a) Petals strap-shaped 

 x. Petals yellow, stamens 4, (staminodia 4) H amamelidaceae 



