Distinguishing Characteristics of Plant Families


  1. Brassicaceae (Cruciferae) Mustard Family
    1. Leaves are often deeply lobed and pinnatifid.
    2. Flowers are actinomorphic and without subtending bracts (ebracteate).
    3. Perianth is of 4 sepals and 4 petals in a cruciform (cross-like) arrangement.
    4. Petals are often clawed.
    5. Stamens are tetradynamous (4 long and 2 short).
    6. Fruit is a special capsule; either a silique (longer than wide) or a silicle (wider than long)
    7. Entomophilous.
    8. Economic genera: Brassica (cabbage, broccoli, turnip, cauliflower, mustard, rutabaga, kohlrabi), Raphanus (radish), Rorippa (watercress), Armoracia (horse radish).


  1. Oxalidaceae. Oxalis or Wood-Sorrel Family
    1. Perennial or annual herbs, often with acrid juice.
    2. Leaves are often palmately compound; mostly trifoliate).
    3. Androecium of 10 stamens, often in 2 whorls, the outer whorl shorter than the inner whorl (sometimes reduced to staminodes).
    4. Gynoecium of 1 pistil, 5 carpels, 5 stigmas.
    5. Fruit a loculicidal capsule, often deeply 5-angled.


  1. Malvaceae. Mallow Family
    1. Plant body with stellate hairs (star-shaped).
    2. Flowers often are subtended by an epicalyx of distinct or connate bracts.
    3. Androecium has numerous stamens with its filaments grouped into a staminal column, called a monodelphous condition.
    4. Fruit is a capsule or schizocarp, usually separating at maturity into one to several 1-seeded segments.
    5. Economic genera: Gossypium (cotton), Abutilon, Hibiscus esculentus (okra), Althaea (hollyhock).


  1. Geraniaceae. Geranium Family
    1. Flowers are actinomorphic with elongated receptacle.
    2. All plants are annuals in the Mojave Desert.
    3. Perianth of 5 sepals and petals.
    4. Fruit is a capsule splitting into 5 segments with a style attached to each.
    5. Fruits often have hygroscopic awns that twist into a corkscrew. As the awns uncoil (when wet) and contract (when dry) in response to moisture, the pointed fruit segment is driven into the ground. Retrorse hairs (barbs) secure the dispersal unit.
    6. Genera is mostly limited here to Erodium.



  1. Zygophyllaceae. Caltrop Family
    1. Leaves mostly opposite, pinnately compound with 2 or 3 or more leaflets. Stipules present, sometimes spiny.
    2. Compound pistil composed of 5 carpels.
    3. Fruit is a hairy schizocarp, splitting into 5 12 indehiscent segments.
    4. Major genus in the family is Larrea tridentata (creosote bush).


  1. Plantaginaceae. Plantain Family
    1. Leaves are basal with parallel venation.
    2. Flowers are small, in a tight cluster at the tip of a leafless stalk (scapose).
    3. Corolla is papery-like, with 4 fused petals, lobes flaring.
    4. Fruit is a pyxis, a capsule that opens by a lid to release seeds.
    5. Seeds are mucilaginous, and have been used as an ingredient in laxative formulas.
    6. Family is represented here by one genus, Plantago.


  1. Hydrophyllaceae. Waterleaf Family
    1. Plant generally with erect, bristly hairs, sometimes with glandular hairs.
    2. The gynoecium has either 2 styles, or 1 forked or bifid style.
    3. Fruit is a capsule.
    4. Major genera in southern Nevada includes Phacelia, Nama, and Eriodictyon (yerba santa).
    5. Inflorescence a coiled cyme, resembling a scorpion.


  1. Boraginaceae. Borage Family
    1. Inflorescence a coiled cyme, one-sided, resembling a scorpion.
    2. Stem hairs are generally bristly and erect.
    3. Flower color is often white or yellow.
    4. Corolla tube often with infoldings or scales (corona).
    5. Fruit is a schizocarp splitting into 4 nutlets.


  1. Cactaceae. Cactus Family

a. See notes on Cactaceae on Website.