Lecture 9 Plant Fertility

Perfect flower

Flower containing both mega- and micro-sporangia (female and male parts) in the same flower

Imperfect flower

Flower containing only megasporangia OR only microsporangia, not both

Monoecious

Mega- and micro-sporangia occur in the same plant (may be in separate flowers), e.g. corn

Dioecious

Mega- and micro-sporangia occur on separate, individual plants (plants are either male or female), e.g. Yaupon Holly

Corn detasseling

Farming practice removing male tassels from "female" corn rows to prevent self-pollination and force cross-pollination for hybrid seed production

Inbreeding depression

Reduction in fitness caused by selfing unmasking deleterious recessive mutations

Self-incompatibility (SI)

Genetic mechanism that rejects self-pollen before fertilization, preventing self-fertilization and promoting outcrossing

S-locus

Highly polymorphic genomic region encoding matching pollen/pistil recognition proteins that underlie self-incompatibility

Heterostyly

Breeding system where a species has floral morphs (e.g., pin and thrum) differing in pistil/stamen length, linked to heteromorphic self-incompatibility

Pin flower

Heterostylous flower morph with a long pistil and short stamens

Thrum flower

Heterostylous flower morph with a short pistil and long stamens

Reproductive assurance

Benefit of selfing that guarantees seed production when pollinators or mates are scarce

Cleistogamy

Production of small, closed, bud-like flowers that never open and self-pollinate, as a backup to open cross-pollinated flowers

Chasmogamous flower

Open, showy, fragrant flower adapted for insect cross-pollination

Cleistogamous flower

Closed, non-opening flower that self-pollinates to guarantee seed set

Pollination syndrome

Set of floral traits (color, shape, scent, reward) that has convergently evolved to match a specific type of pollinator

Buzz pollination

Pollination method where bees vibrate flowers with pore-opening stamens to shake out pollen

Carrion mimicry

Floral strategy of mimicking the color and smell of rotting flesh to attract flies as pollinators (e.g., skunk cabbage, pawpaw)

Darwin's star orchid

Orchid with an extremely long nectar spur; Darwin predicted a moth with an equally long proboscis to pollinate it, confirmed decades later

Mimulus lewisii

Pink, wide-corolla monkeyflower species pollinated by bees, with concentrated but smaller nectar reward

Mimulus cardinalis

Red, tubular monkeyflower species pollinated by hummingbirds, with reflexed petals, exserted stamens/stigma, and larger nectar volume

Pre-zygotic isolation

Reproductive isolation occurring before fertilization, e.g. pollinator preference driven by flower color/nectar differences between related species

Co-evolution (plant-pollinator)

Reciprocal evolutionary change between plants and their pollinators, driving diversification of both groups

Fruit

Mature ovary (sometimes plus accessory tissue) containing seeds; protects seeds and aids dispersal

Berry

Fruit from a single carpel or multiple fused carpels of one flower (e.g., avocado)

Aggregate fruit

Fruit formed from multiple pistils/carpels of a single flower, fused or unfused (e.g., magnolia)

Multiple fruit

Fruit formed from a fused mass of many individual flowers (e.g., pineapple)

Samara

Winged, wind-dispersed fruit (e.g., maple)

Vivipary

Condition where seeds begin to germinate while still attached to the parent plant (e.g., mangroves)

Abiotic dispersal

Seed/fruit dispersal via non-living agents such as wind or water

Biotic dispersal

Seed/fruit dispersal via living agents such as animals

Anachronistic dispersal

Fruit traits evolved to be dispersed by now-extinct megafauna, persisting via other means today (e.g., Osage orange and Pleistocene ground sloths)

Birdcatcher tree (Pisonia)

Plant with sticky seeds that attach to birds for dispersal between islands; can trap and kill small birds, enriching soil

Wind pollination

Pollination syndrome with inconspicuous, scentless, nectarless flowers; abundant small light pollen; exposed feathery stigmas; causes allergies