Question: How can yeast make flowers more attractive to pollinators?
About the article "Yeast", section "Ecology".

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One hypothesis as to how unrewarding species can persist in the population is that they only receive visits from naive pollinators.
As pollinators do not appear to be able to distinguish between rewarding and unrewarding flowers prior to landing, they need to make test visits so they can learn to avoid particular morph types.
When a preferred rewarding morph type becomes locally depleted, pollinators may be initially attracted to unrewarding morphs if these morphs exploit signals that are innately attractive or closely mimic rewarding species.
However, under this hypothesis, the pollinator should learn to associate this morph with no reward and consequently avoid it on future foraging bouts. 
Nectar guides are markings or patterns seen in flowers of some angiosperm species, that guide pollinators to their rewards.
Rewards commonly take the form of nectar, pollen, or both, but various plants produce oil, resins, scents, or waxes.
Such patterns also are known as "pollen guides" and "honey guides", though some authorities argue for the abandonment of such terms in favour of floral guides (see for example Dinkel & Lunau).
These patterns are sometimes visible to humans; for instance, the Dalmatian toadflax ("Linaria genistifolia") has yellow flowers with orange nectar guides.
However, in some plants, such as sunflowers, they are visible only when viewed in ultraviolet light.
Under ultraviolet, the flowers have a darker center, where the nectaries are located, and often specific patterns upon the petals as well.
This is believed to make the flowers more attractive to pollinators such as honey bees and other insects that can see ultraviolet.
This page on butterflies shows an animated comparison of black-eyed Susan ("Rudbeckia hirta") flowers in visible and UV light.
The ultraviolet color, invisible to humans, has been referred to as "bee violet", and mixtures of greenish (yellow) wavelengths (roughly 540 nm) with ultraviolet are called "bee purple" by analogy with purple in human vision. 
"C. thyrsiflorus" can grow more than tall in its native chaparral habitat.
Flowers vary from different shades of blue to close to white.
It is popular with birds, butterflies, and other pollinators. 
Chasmogamy is a botanical term describing a type of flower.
A chasmogamous flower opens at maturity, exposing stamens and style to allow fertilization.
The style receives pollen from another individual.
Chasmogamous flowers also provide pollen to other plants.
This is the opposite of cleistogamy, in which a plant produces flowers that stay closed and fertilize themselves.
A cleistogamous flower is usually smaller and requires less energy to produce.
It is also structured to bring its reproductive organs into contact, making it more likely that fertilization will be successful.
Fertilization in a chasmogamous flower depends on the receipt of appropriate pollen, and often fails.
Chasmogamous flowers are structured to maximize the receipt of pollen; they are generally larger and showier with markings such as nectar guides to facilitate the entrance of pollinators such as insects.
They produce nectar, the reward sought by pollinating organisms, and are sometimes scented to attract them.
The petals of a chasmogamous flower can be attractive to pollinators; cleistogamous flowers often lack petals.
Chasmogamy is a mechanism that can increase fitness via the exchange of genes between individuals.
Cleistogamy is favored is stressful conditions, however, when producing large, complex flowering structures is costly to a plant.
Cleistogamous flowers also occur in the absence of pollinators.
Some chasmogamous flowers self-fertilize.
Some undergo delayed selfing, in which they attract pollinators to promote cross-fertilization, and then self-fertilize later if unsuccessful.
Some species have mixed mating systems, producing both chasmogamous and cleistogamous flowers.
The ratio of flower types is often influenced by environmental conditions. 
Ecologically, prairie restoration aids in conservation of earth's topsoil, which is often exposed to erosion from wind and rain when prairies are plowed under to make way for new commerce.
Conversely, much more of the prairie lands have become the fertile fields on which cereal crops of corn, barley and wheat are grown.
Many prairie plants are also highly resistant to drought, temperature extremes, disease, and native insect pests.
They are frequently used for xeriscaping projects in arid regions of the American West.
A restoration project of prairie lands can be large or small.
A backyard prairie restoration will enrich soil, help with erosion and take up extra water in excessive rainfalls.
Prairie flowers are attractive to native butterflies and other pollinators.
On a larger scale, communities and corporations are creating areas of restored prairies which in turn will store organic carbon in the soil and help maintain the biodiversity of the 3000 plus species that count on the grasslands for food and shelter.