Inflorescences HortBotany Solitary Flowers

Inflorescences

• HortBotany

Solitary Flowers

• Some species of plants produce solitary flowers.
• Solitary flowers are are borne singly and separate from one another.

• Saucer Magnolia solitary flowers

Solitary Flowers

• Another example of a plant that bears solitary flowers is Bloodred Geranium.

• Many solitary flowers on Bloodred Geranium (Geranium sanguineum)

What is an inflorescence?

• In other species of plants many, small flowers are borne together in dense clusters called inflorescences.
• There are many types of inflorescences. Each type of inflorescence is determined by how the flowers are arranged.
• Inflorescences are a useful plant ID tool.

Common Inflorescences

• Spike
• Raceme
• Panicle
• Umbel
• Corymb
• Cyme
• Composite Head

Spike

• Individual flowers are sessile (without pedicels).
• Lower flowers open first.
• Indeterminate.

• spike

Spike

• Gladiolus ‘Lavadandy’ flower spike (image courtesy of Columbia View Gladiolus)

• Gladiolus

Raceme

• Individual flowers have pedicels.
• Pedicels can vary in length from species to species.
• Lower flowers open first.
• Indeterminate.

• raceme

• pedicel

• peduncle

Raceme

• Itea virginica, Virginia Sweetspire produces dense, pubescent racemes.
• The flowers have short pedicels and the inflorescence resembles a spike.

• Virginia Sweetspire

Raceme

• Dicentra spectabilis, Bleeding Heart, produces a one-sided raceme of pink, heart-shaped flowers.

• Bleeding Heart

Panicle

• A highly branched inflorescence consisting of many, repeating units.
• Panicles can be made of many spikes, racemes, corymbs, or umbels.
• Indeterminate.

• A panicle of racemes

Panicle

• Syringa vulgaris, Common Lilac, produces panicles.

• Common Lilac

Panicle

• Aesculus glabra, Ohio Buckeye, produces 4-7” long panicles.
• This tree is located near the Kirkwood library.

• Ohio Buckeye

Umbel

• Individual flower pedicels all originate from the same spot on the peduncle.
• Outer flowers open first.
• Indeterminate.

• peduncle

• pedicel

Umbel

• Allium ‘Jade Eyes’, image courtesy of Breck’s.
• Often, umbels are globe-shaped like this one.

• Allium

Corymb

• Somewhat similar to the umbel.
• Individual flower pedicels are attached to the peduncle at different points.
• Often flat-topped.
• Outer flowers open first.
• Indeterminate.

• corymb

• pedicel

• peduncle

Corymb

• Pyrus calleryana, Callery Pear, is a beautiful, spring-flowering tree covered with corymbs of white flowers.

• Callery Pear

Cyme

• In real life, cymes tend to be flat or convex shaped.
• The inner flowers open first.
• Determinate.

• cyme

Cyme

• Cymes are often compound as shown in the illustration to the right.

• compound cyme

Cyme

• Viburnum x juddi, Judd Viburnum, produces cymes of light pink flowers in late April. The flowers have a pleasing, spicy fragrance

• Judd Viburnum

Cyme

• Viburnum dentatum, Arrowwood Viburnum, produces cymes of white flowers that are not fragrant.

• Arrowwood Viburnum

Corymbs vs. Cymes

• Often these two types of inflorescences can look a lot alike.
• Remember that corymbs are indeterminate, they continue to elongate as the season progresses. Cymes are determinate and do not continue to elongate as the growing season progresses. Also, the inner flowers of cymes open first.

Composite Head

• A highly advanced inflorescence.
• Consists of separate ray and disk flowers
• Bracts may be green, but can also be colored(Strawflower).

• ray flower

• disk flower

• bract

Composite Head

• Helianthus annus, Sunflower, produces a large composite head.
• After pollination and fertilization, each disk flower becomes a single-seeded fruit.

• Sunflower

Composite Head

• Echinaceae purpurea, Purple Coneflower (image courtesy of Wildflower Farm).
• Composite head with purple ray flowers and brown disk flowers.

• Purple Coneflower

Review Time!

What’s this?

• Umbel

What’s this?

• Raceme

What’s this?

• Corymb

What’s this?

• Composite Head

What’s this?

• Panicle

What’s this?

• Spike

What’s this?

• Cyme

The End