Month: November 2023

The Asteraceae family, also known as the aster, daisy, or sunflower family, is one of the largest and most diverse plant families, comprising over 32,000 species. Here are some defining characteristics:

1. Inflorescence: Flowers are arranged in compact clusters known as heads or capitula. Each head may appear as a single flower, but it is actually a cluster of many small flowers grouped together on a common receptacle.
2. Bracts: The base of the flower head is surrounded by a set of specialized leaves called bracts. These bracts often resemble petals and play a role in attracting pollinators. The arrangement of bracts can be important in distinguishing different genera or species within the family.
3. Flower structure: Each flower head typically consists of two types of flowers—central disk flowers and outer ray flowers. The disk flowers are tubular and found in the center, while the ray flowers have a strap-shaped structure and radiate outward. However, some species may lack one of these types.
4. Fruit: The fruits are often achenes, which are small, dry, one-seeded fruits. A characteristic feature is the presence of a pappus—a structure attached to the seed that aids in wind dispersal.
5. Alternate leaves: The leaves are usually alternate, meaning they are arranged along the stem in a staggered fashion. The leaves may be simple or compound.
6. Milky latex: Many species in the Asteraceae family produce a milky latex when injured. This latex can be a defensive mechanism against herbivores.
7. Habitat: Members of the Asteraceae family are found in a wide range of habitats, from arctic tundra to tropical rainforests, and from deserts to alpine meadows.
8. Economic importance: The family includes many economically important plants, such as sunflowers (Helianthus), daisies (Bellis), marigolds (Tagetes), and chrysanthemums (Chrysanthemum). Some species are cultivated for ornamental purposes, while others are important food crops or sources of medicinal compounds.

Jepson Herbarium video showing characteristics of the family.

Key to the Asteraceae.

The Solanaceae, commonly known as the nightshade family, includes many economically important and widely cultivated species. Some of the defining characteristics of the Solanaceae:

1. Alkaloids: Many produce alkaloids, which are nitrogen-containing compounds that often have pharmacological effects. Examples include nicotine in tobacco, atropine in belladonna, and solanine in potatoes.
2. Alternate leaves: may be simple or compound.
3. Inflorescence: cymes or umbels.
4. Five-lobed corolla: flowers with five petals and five sepals
5. Stamens: five.
6. Superior ovary: positioned above the attachment of other floral parts.
7. Fruit type: berries (e.g., tomatoes), capsules (e.g., tobacco), and other types.
8. Economic importance: tomatoes (Solanum lycopersicum), potatoes (Solanum tuberosum), bell peppers (Capsicum annuum), and eggplants (Solanum melongena). Additionally, tobacco (Nicotiana tabacum) is a member of this family.
9. Herbaceous or woody habit: Tomatoes and potatoes are herbaceous, while some trees, like certain species of Brugmansia, are woody.

Video showing characteristics of the Solanaceae.

Jepson key to the Solanaceae.

The Ericaceae, the heath or heather family, includes a wide variety of plants, many of which are adapted to acidic and nutrient-poor soils. Here are some defining characteristics:

1. Leaves: often evergreen, simple, and alternate. They may be needle-like or broad and can be arranged in a spiral or whorled pattern.
2. Habitat: Many found in acid soils, particularly in heathlands, moors, and pine barrens. They are often associated with nutrient-poor environments.
3. Flowers: Typically bisexual and often symmetrical. They have a bell-shaped or tubular structure and are often arranged in clusters. The floral parts are usually in multiples of four or five.
4. Calyx: Usually present and may be fused into a tube. It often persists in the fruiting stage.
5. Corolla: May be fused into a tube and is often urn-shaped or bell-shaped.
6. Fruit: Often a capsule or berry.
7. Mycorrhizal Associations: Many form symbiotic relationships with mycorrhizal fungi, which help them absorb nutrients, especially in nutrient-poor soils.
8. Economic Importance: Well-known members of the Ericaceae include blueberries (Vaccinium), cranberries (Vaccinium macrocarpon), and rhododendrons (Rhododendron).

Here’s a video from the Jepson herbarium about Arcostaphylos patula.

Follow this link to the Jepson key to CA Ericaceae.

The Rosaceae family, commonly known as the rose family, is a diverse group of flowering plants. There are several identifying characteristics:

1. Leaves: Compound leaves, which means the leaves are divided into multiple leaflets arranged along a central stem or petiole. The leaflets may be toothed or lobed.
2. Flowers: Five-petaled and with radial symmetry. They come in various colors, such as white, pink, red, or yellow. The flowers can be solitary or arranged in clusters.
3. Fruit: Fleshy, one-seeded “drupe” or a “pome,” which is a fruit with a central core containing seeds. Examples of pome fruits include apples and pears, while drupe fruits include cherries and plums.
4. Sepals: Often fused together at the base in a cup-like structure called a hypanthium.
5. Petals: Typically separate and attached to the receptacle of the flower.
6. Stamens: Numerous stamens.
7. Carpels: The number of carpels varies among different species within the family. They are usually located at the center of the flower.
8. Stipules: Many species have stipules, which are small leaf-like structures at the base of the leaf petiole.
9. Prickles and Thorns: Some Rosaceae plants have prickles or thorns on their stems, providing them with a defensive mechanism.
10. Alternate Leaves: The leaves of Rosaceae plants are often arranged alternately along the stems, although exceptions exist.
11. Economically Important Species: The Rosaceae family includes a wide range of economically important plants, such as roses (ornamental), apples, pears, peaches, strawberries, raspberries, and many other fruits, as well as some ornamental and medicinal plants.

Link to a video from the Jepson herbarium showing characteristics of the Rosaceae.

Link to the Rosaceae key.