[permaculture] Crabgrass || Re: crabgrass & bermuda graa/Charles waters' book

Lawrence F. London, Jr. lfl at intrex.net
Fri Jun 15 23:35:27 EDT 2007


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How to read a taxobox
Digitaria sanguinalis
Digitaria sanguinalis
Scientific classification
Kingdom: 	Plantae
Division: 	Magnoliophyta
Class: 	Liliopsida
Order: 	Poales
Family: 	Poaceae
Subfamily: 	Panicoideae
Genus: 	Digitaria Haller

See text.

Digitaria is a genus of about 300 species of grass (family Poaceae) native to tropical and warm temperate regions. 
Common names include crabgrass, finger-grass, and fonio. They are slender monocotyledonous annual and perennial lawn, 
pasture, and forage plants; some are often considered lawn pests. Digitus is the Latin word for "finger", and they are 
distinguished by the long, finger-like inflorescences they produce.

All crabgrasses have similar growth habits and flowering structures, but species are separated by minor differences in 
the flower structures and leaf pubescence.[1] They typically have spreading stems with wide flat leaf blades that lay on 
the ground with the tips ascending. The inflorescence is a panicle in which the spike-like branches are arranged in 
digitate fashion. The spikelets are arranged in two rows on an angled or winged rachis. Each spikelet has two florets, 
only one of which is fertile. The first bracts at the base of the spikelets are either very minute or absent.[2]

Crabgrass seed has a menstration germination period; if conditions are right, it can germinate throughout the growing 
season. Crabgrasses occur in tropical, subtropical, and temperate regions of both hemispheres.

Despite their weediness, crabgrasses do have a few redeeming qualities. The seeds, most notably those of fonio, can be 
toasted and ground into a flour, which can be used to make porridge or fermented to make beer. Fonio has been widely 
used as a staple crop in parts of Africa. It also has decent nutrient qualities as a forage for cattle.

     * 1 Lawns
     * 2 Selected species
     * 3 Images
     * 4 References

[edit] Lawns

The most prevalent species of Digitaria in North America are Large Crabgrass (D. sanguinalis), sometimes know as Hairy 
Crabgrass; and Smooth Crabgrass (D. ischaemum). These species often become problem weeds in lawns and gardens, growing 
especially well in lawns that are watered lightly, underfertilized, poorly drained, and growing thinly.[3] They are 
annual plants, and one plant is capable of producing 150,000 seeds per season. The seeds germinate in the late spring 
and early summer and outcompete the domesticated lawn grasses and expand outward in a circle up to 12 inches in 
diameter. In the fall when the plants die they leave large voids in the lawn. The voids then become prime areas for the 
crabgrass seeds to germinate the following season. Crabgrasses also have a different texture and color that often 
interrupts the uniformity of a lawn. In vegetable gardens, crabgrass can quickly out-compete desirable plants, causing 
yield reductions. Crabgrasses can be controlled with pre-emergent herbicides that interfere with a key enzyme when a 
seed germinates. These herbicides must be applied at a critical time. If they are applied to the soil too early, they 
get washed too deep into the soil by rainwater. If they are applied too late the key enzyme inhibited is no longer 
active. The rule of thumb is to apply when the local forsythia blooms are wilting.

[edit] Selected species

     * Digitaria ammophila Silky Umbrella Grass
     * Digitaria bicornis Finger Grass
     * Digitaria brownii Cotton Panic Grass
     * Digitaria californica Arizona Cottontop
     * Digitaria ciliaris Summer Grass, Southern Crabgrass
     * Digitaria ctenantha Comb Finger Grass
     * Digitaria didactyla Queensland Blue Couch
     * Digitaria eriantha Pangolagrass
     * Digitaria exilis Fonio
     * Digitaria filiformis Slender Crabgrass
     * Digitaria gracillima Longleaf Crabgrass
     * Digitaria horizontalis Jamaican Crabgrass
     * Digitaria ischaemum Smooth or Small Crabgrass, Smooth Finger-grass
     * Digitaria longiflora Indian Crabgrass
     * Digitaria milanjiana Madagascar Crabgrass
     * Digitaria nuda Naked Crabgrass
     * Digitaria pauciflora Twospike Crabgrass
     * Digitaria radicosa Trailing Crabgrass
     * Digitaria sanguinalis Hairy Crabgrass, Northern Crabgrass, Hairy Finger-grass, Pigeon Grass, Large Crabgrass
     * Digitaria serotina Dwarf Crabgrass
     * Digitaria texana Texas Crabgrass
     * Digitaria velutina Velvet Crabgrass
     * Digitaria villosa Shaggy Crabgrass
     * Digitaria violascens Violet Crabgrass
     * Taxonomic relationsip of Digitaria in Pakistan
     * New subspecies of Digitaria sanguinalis from Pakistan

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