COI.ORADO Weed Seeds 
21 
Following are the noxious weed seeds of Colorado as enumer- 
ated in the Colorado Seed Act : 
Common Name 
Botnnieal Name 
Description 
on 
Page 
Large Crab-grass 
Syntherisma sanguinaie . . 
Small Crab-grass 
Syntherisma humifusum . 
Wild Oat 
Avena fatua 
Wild Barley 
Hordeiim jubatum 
Chess 
Bromus secalinus 
Wild Buckwheat 
Polygonum convolvulus . . . 
Corn Cockle 
Agrostemma githago 
Cow Cockle 
Vaccaria vaccaria 
Wild Mustard 
Brassica arvensis 
White Mustard 
Brassica alba 
Indian Mustard 
Brassica juncea 
Black IMustard 
Brassica nigra 
Low Hop Clover 
Trifolium procumbens . . . . 
Field Dodder 
Cuscuta arvensis 
Large-seeded Alfalfa Dodder 
Cuscuta indecora .... 
Small-seeded Alfalfa Dodder 
Cuscuta planiflora 
Black-seeded Plantain 
Plantago rugelii 
Buckliorn Plantain 
Plantago lanceolata 
Common Plantain 
Plantago major 
68 
Pursh’s Plantain 
Plantago purshil 
Poverty Weed 
Franseria tomentosa 
70 
Poverty Weed 
Iva axillaris 
Canada Thistle 
Carduus arvensis 
.76 
Annual Sow Thistle 
Sonchus oleraceus 
80 
Field Sow Thistle 
Sonchus arvensis 
.81 
Spiny Sow Thistle 
Sonchus asper 
.80 
/. 
GRASS FAMILY 
Gramincae 
The grass inflorescence or flowering group is made up of 
spikelets. A spikelet (Fig. 12), as the unit of inflorescence, con- 
sists of a stalk or axis 
(rachilla) bearing a number 
of two-ranked (distichous) 
bracts (glumes) the lowest 
two of which are empty. 
Above the two empty 
glumes, which subtend each 
spikelet, and attached to the 
rachilla, are one or more 
flowers. Each flower is borne 
in the axil of a bract called 
the lemma and subtended 
or enveloped by a two- 
keeled bract opposite the 
lemma, commonly refer- 
, i*ed to as the palet or palea. 
I he back of the palet is toward the rachilla. The palet usually 
envelops the other parts of the flower with its infolded edges. 
