Colorado Weed Seeds 
35 
(, 
Fig. 41. Slender Nettle 
(Urtica gracilis). A. Calyx 
enclosing achene. B. Achenes. 
X 15. 
Slender Nettle ( Urtica gracilis 
Ait.) (Fig. 41).— Seeds light wood- 
brown in color, dull, often roughened, 
ovate, compressed, summit terminating 
in a small knob-like projection; calyx 
somewhat persistent and armed at tne 
base with several stinging hairs; seeds 
.S-1 mm. long, .5-.6 mm. wide. 
5. BUCKWHEAT FAMILY 
(Polygonaceae) 
Ovary 1-celled, bearing a single, erect seed; fruit usually an 
achene; either double convex, compressed, 3-angled or rarely 
1 4-angled, usually wholly or partly enclosed by the persistent calyx ; 
' seed shaped like the pericarp; endosperm mealy. 
Key to Genera 
Seeds margined or winged, usually enclosed by the calyx l..Rumex 
Seeds not margined or winged, and seldom enclosed by the calyx 2 . .Polygonum 
1. Dock, Sorrel 
{Rumex L.) 
Achenes 3-angled rarely 4-angled, with equal sides, distinctly winged 
or margined or with a persistent calyx; embryo curved or nearly straight, 
borne in one of the faces of the achene. 
Key to Species 
Seeds with distinct, flaring, calyx wings 
Seeds without flaring calyx wings 
Seed edges obtuse or rounded 
Seeds edges acute or sharp 
1. 
.R. 
crispus 
2. 
.R. 
acetosella 
3. 
.R. 
persicarioides 
1. Curled Dock, Yellow Dock 
{Rumex crispus L.) (Fig. 42). — Seeds 
bay color, shiny, 2-2.5 mm. long, 1.5-2 
mm. wide, 3-angled, sides equal, edges 
sharp or acute; sides slightly concave 
near the apex, which is abruptly acute. 
Fig 42. Curled Dock 
(Rumex crispus). a. Calyx en- 
closing achene. x 9. b. Achene. 
X 6. 
2. Sheep Sorrel, Field Sorrel 
{Rumex acetosella L.) (Fig. 43). — Seeds 
mahogany-red to bay color, sniny, perstsi- 
ent, roughened calyx usually present ; 
achenes 1 mm. long, .8-1 mm. wide, 3- 
angled ; sides equal, edges blunt or obtuse ; 
sides slightly convex. 
Fig. 43. Sheep Sorrel 
(Rumex acetosella). A. 
Achene. B. Calyx enclosing 
aclune. x B5. 
I 
