3.2 Weed Biology – Perennial Weed Strategies

Weeds have developed amazing strategies to survive even the harshest of environmental conditions.  Part of that includes their options for reproduction.  Perennial weeds can reproduce via seeds and/or vegetative structures.  Those that reproduce only via seeds are called simple perennials, while those that can also reproduce through vegetative means are called creeping.

A few key concepts regarding the simple types:

• Germinate from seeds.
• Grow vegetative tissue and form a crown.
• The crown has root buds that overwinter and in the next spring produce new shoots for the same plant.
• Examples: dandelion (Taraxacum officinale), curly dock (Rumex crispus L.)

A few key concepts regarding the creeping types:

• Germinate from vegetative propagules or seeds
• Adventitious buds in propagules can generate new shoots or roots.
• Very aggressive and hard to control plants.
• Examples: canada thistle (Cirsium arvense (L.) Scop)  and johnsongrass (Sorghum halepense (L.) Pers.)