Agrostology Flashcards
What are the floristic characteristics of grasses?
- main floristic part = spikelet
- spikelet is composed of glumes and florets
What is a glume?
- type of scale or bract
- glumes are the 1st and 2nd scale at the base of the spikelet
- they comprise the base of the spikelet
What is a rachilla and rachis?
Rachilla:
- the stem inside a spikelet
- center stem of spikelet
Rachis:
- outside of glume
- branch coming off of main stem (culm)
What are scales?
- scales are small leaf-like structures at the base of the spikelet
- they always alternate NOT opposite
What is a lemma?
- compose the floret
- lemma is outermost scale
- apex of lemma may extend into slender bristle-like appendages known as awn
What is a palea?
- compose the floret
- the innermost scale
- shorter than lemma
What is a point of insertion?
What is pubescence?
- has long silky hairs at base like a bluegrass or no pubescence like a bromegrass
What are nerves?
- there is silica covering the nerves that makes textured ridges
- always paired on either side of midrib so in total there is an odd number
What are the reproductive parts of a grass?
- ovary
- the seed producing part of the flower
- stigma
- the part on which pollen adheres and germinates
- stamens
- male organ of a flower
What is inflorescence?
- section of the axis with spikelets
- three main types:
- Panicle
- Raceme
- Spike
What are the two life spans of grasses?
- perennial
- thickened structures at base of plant
- well developed root system
- remnants from previous year’s stems or leaves present
- rhizomes or stolons occurs
- annual
- shallow, fibrous root system
- plants are smaller than perennials
What are the different types of plant form?
- densely tufted
- well developed crown, many aggregated culms (stem), clearly defined perimeter and often lack rhizomes e.g. bunch grass
- loosely tufted
- small clusters of loosely connected stems, often have rhizomes
- sod-forming
- many, non clustered stems and strongly rhizomous e.g. quack grass or lawn grass
- Densely tufted can sometimes produce rhizomes and can be loosely tufted as well
QUACK GRASS CAN BE ALL THREE
What are stem or culm characteristics?
- grass stem orientations
- upright and erect
- lying flat near soil surface
- bent or curved at base
What is a stolon?
Stolon
- creep above soil surface
- are fibrous
What is a rhizome?
Rhizome
- grow below the soil surface e.g. quack grass
What is a sheath?
- the sheath is the portion of the leaf that covers the stem on grasses and sedges
- can be split or closed
What is an auricle?
- extensions of the leaf blade and sheath
- wrap around the stem of grass plants
What is a collar?
- small ring of tissue separating the sheath and blade at the stem
- may vary in width and covered with fine hair or smooth
What is a ligule?
- small membranous tissue on the inside of the leaf blade between the blade and the sheath
- may be absent in some grass species
- vary from narrow fringe of hairs to large membranous structures
What is a blade?
- blade is the part of the leaf above the sheath, collar and ligule
How to use floristic keys to identify grasses (groups vs tribes)
Group Tribes
I Paniceae (Millet)
IIa Hordeae (Barley)
IIb Chloridae (Grama
III Festuceae (Fescue)
IV Aveneae (Oats)
V Agrostidae (Bentgrass)
pg. 42 Phalarideae (Canary)
What is the difference between sedges, rushes and grasses?
- sedges have edges
- rushes are round
- grasses are hollow
The structure of a sedge stem and leaves:
Parts of sedge:
- septate - nodulose
- triangular stem
- leaves are three ranked
The leaves are three ranked e.g. has three rows
What is the rooting structure of sedges?
- similar to grasses, sedges can have either spreading rhizomatous or lumped tufted roots
