Parasitic Plants

Name for device parasitic plants use to attach themselves to hosts?

A haustorium, specialized absorbing organ

How are parasitic plants classified?

Stem parasites- mistletoe, dodder

Root parasites- Striga (witchweed), broomrape

Explain the nutritional dependence of parasitic plants

Can be holoparasitic, with little to no chlorophyll and rely entirely on plant’s phloem/xylem

Or can be hemiparasitic, still photosynthetic and mainly feed on plant xylem for water/minerals

How does parasitic dependence vary?

Species can either be obligate, relying entirely on plants for their development, or facultative, which can grow without a host.

Mistletoes (Santalaceae)

Preferred hosts are hardwoods and are stem hemiparasites.

Cause growth reduction, economic threat to forestry. Disperse via sticky seeds excreted by birds, dwarf mistletoes disperse with explosive capsules

Management options include pruning, tree removal, controlled burns, IFM

Broomrapes (Orobanchaceae)

Witchweed (Orobanchaceae)

Quarantined in Southeast, not present in CA.

Leafy vs dwarf mistletoes

Dwarf- small and leafless, parasitizes conifers, are highly damaging and have a great impact on forestry

Leafy- Green oval-shaped leaves, parasitizes mostly flowering trees, rarely kills hosts

Sandalwoods

Unlike other genera it’s family, it’s a root hemiparasite. Obtains 50—60% of water/minerals from host. Cultivated for their fragrant wood, host trees are planted nearby to encourage growth

Cuscuta (Convolvulaceae)

Stem holoparasites, threat to legumes like alfalfa. Spread canopy to canopy, with seeds that remain viable for 5-10 years in the soil

Management options- destroying infested stands, early herbicide applications, crop rotations, quarantines and using clean seed when planting.