lab manual


<< Lab 4 Rosids I: Oxalidales (Oxalidaceae), Malpighiales (Violaceae, Hypericaceae, Salicaceae), Rosales (Rosaceae, Rhamnaceae), Fabales (Fabaceae), Cucurbitales (Cucurbitaceae), Fagales (Fagaceae, Betulaceae, Juglandaceae); Asterids: Cornales (Cornaceae, Hydrangeaceae), Ericales (Polemoniaceae) >>



Oxalidaceae - We have one genus in this family in CA. About half of the species are non-native, but we have several beautiful natives as well.

  • Oxalis "sorrel"
    This genus gets its name from the oxalic acid that is found in its stems and leaves. (If you taste the plant, it tastes sour.) In California, the members of this genus are herbs with trifoliolate leaves and leaflets that are often obcordate in shape. The leaflets exhibit "sleep movements", raising and lowering with light level. Althought the leaves superficially resemble those of clover, the flowers are 5-merous and radially symmetrical. Look at the stamens. Are they all of equal height? _________ How many styles and stigmas are there? _____ Compare the stamen heights to the style/stigma heights. What is the significance of these observations?



Violaceae - In California, there is only one genus, and the majority of the species are native.

  • Viola "violet, pansy"
    Short, annual or perennial herbs with bilateral flowers. The leaves are often palmately veined, sometimes cordate, sometimes dissected or compound. How would you describe the inflorescence in this genus? _____________________ Each flower has a corolla made up of five petals, with two upper petals, two side petals, and a lower single petal. Contrast this with the arrangement in the Papilionoideae; is the unpaired petal - the banner - lowermost or uppermost in the flower in that subfamily? __________________
    In Viola, the lower petal has a nectar spur which is fed by nectaries on the filaments of the lowermost two stamens. The stigma has a flap that opens and closes. When a bee probes the spur to obtain the nectar, it pushes open and deposits pollen on the stigma flap; as the bee withdraws from the flower, the flap closes, and at the same time, the anthers shower the bee with pollen; this arrangement prevents the flower from self-pollinating.


Hypericaceae - In California, there is only one genus, and half of the species are non-native. Some taxonomists lump this family into a larger group called Clusiaceae which has the alternate name Guttiferae.

  • Hypericum
    Annuals, perennials, or shrubs with opposite, entire leaves. The leaves are often dotted with translucent or dark glands. The radial flowers have a yellow corolla with 5 free petals. There are many stamens which are sometimes grouped into bunches. How many styles are there? ____________
    One of the species of this genus, H. perforatum, is "St. John's wort", a medicinal herb sold in most drugstores.


Salicaceae - In California, there are two genera in this family with very few non-native species. The seeds in this family have soft cottony hairs attached to them. How are the seeds dispersed? _________________

  • Populus "poplar, cottonwood, quaking aspen"
    Dioecious trees with rather pale bark and deciduous, ovate to deltoid, serrated leaves, sometimes with a flattened petiole. These species enjoy "having their feet in the water" - growing right at the edge of drainages. Some species, such as quaking aspen, are clonal (when you see what you think is a population of this species, it may just be one individual). The flowers are not notable, being small and arranged in catkins. The name "cottonwood" comes from the silky hairs attached to the seeds. The name "quaking aspen" comes from the way the leaves tremble in the wind - a distinguishing feature of these trees.

  • Salix "willow"
    Dioecious, deciduous shrubs or trees that are an important component of our riparian woodlands. There are 29 species in California (a few are non-native). The leaves are alternate, often narrow and elongate, and often stipulate. The buds are distinctive in having only one bud scale. In some species, the flowers appear before the leaves. The flowers (male and female) are small, lacking in perianth, and arranged into catkins with each flower subtended by a single bract. Many people think that these species are wind-pollinated, because of their reduced flowers. However, look carefully at the flowers and you will see that each one has a small nectary. They are actually bee-pollinated.
    The key to Salix species in the Jepson Manual has three separate keys - one for staminate plants, one for pistillate plants, and one for sterile plants (not yet in or past flower). So, you will never have an excuse for not keying out a sample! However, the species are variable, and some consider this a difficult genus to key.



Rosaceae - A large and important mostly temperate-zone family that is quite well-developed in California (46 genera). The members of this family are diverse (herbs to trees), but all have a hypanthium which may be short or long. The calyx and corolla are 5-merous, there are 10 - many stamens, and the gynoecium is variable. Some taxa have numerous separate pistils (each made up of how many carpels? ________), others have a single carpel, and some taxa have a compound pistil with an inferior ovary.
How would you differentiate this family from Ranunculaceae? _________________________
How would you differentiate it from Grossulariaceae or Saxifragaceae? _____________________________

The following are "to-know" genera of the Rosaceae:

  • Prunus "plum, cherry, apricot, almond, peach"
    We have native and non-native species in this important genus. All but one of our species are deciduous. We looked at this genus early on in our floral morphology lab. The flowers have just one carpel. The hypanthium is well-developed but completely free of the ovary. The fruit is a drupe. The leaves often have paired glands on the blade margins and/or on the petioles.

  • Cercocarpus "mountain mahogany"
    A relatively common genus of evergreen shrubs in California. The leaves usually have very straight, regular (and parallel) secondary veins; the margins are usually serrated. The flowers are similar to Prunus in having just one carpel. Does that carpel have a superior or inferior ovary? _______________________ Note the long hairy style which becomes feathery in fruit. The fruit is an achene. (How do you think this fruit is dispersed?)

  • Adenostoma fasciculatum "chamise"
    This shrub is an important dominant of our chaparral vegetation. The leaves are tiny and drought-adapted. The white flowers are very small, each with just one pistil. The fruit is an achene.

  • Rubus "blackberry, raspberry"
    Perennial herbs or shrubs, sometimes wandering, forming brambles. Prickles often present on the stem and/or leaves. Leaves simple to compound. Flowers with many pistils, each becoming a drupelet.

  • Rosa "rose"
    Shrubs or vines. Prickles often present on the stem. Leaves usually compound. Flowers with many pistils surrounded by a well-developed hypanthium (rose hip). Are the ovaries superior or inferior? __________________ The fruit is an achene.

  • Heteromeles arbutifolia "toyon, Christmas berry"
    Tree bearing evergreen, serrated leaves that grows in our mixed evergreen forests. Flowers white, small, grouped into a showy panicle. The pistil of the flowers is compound. The fruit is a pome; knowing this, is the ovary of the pistil superior or inferior? ______________

Other genera and species of the Rosaceae that may be on display:

  • Chaemaebatia foliolosa "mountain misery"
    A fragrant species with highly divided leaves and white flowers, found in the Sierra Nevada where it carpets the forest floor in the yellow pine belt.

  • Duchesnea indica "mock-strawberry"
    A non-native strawberry look-alike that has long stolons and yellow flowers. The receptacle swells in fruit but is not as pulpy as in strawberry (Fragaria).

  • Lyonothamnus floribundus "Catalina ironwood"
    Evergreen tree with exfoliating bark and opposite, pinnately compound leaves. This interesting species, now endemic to the Channel Islands of southern California, was once widespread on the mainland (according to data obtained from the fossil record).

  • Malus "apple" or Pyrus "pear"
    Deciduous trees with alternate serrated leaves. The clusters of flowers usually appear after the leaves (unlike some Prunus). The flowers have one compound pistil with an inferior ovary. Fruit a pome.

  • Physocarpus capitatus "ninebark"
    Deciduous shrubs with palmately lobed leaves and white flowers. Fruits are follicles.


Rhamnaceae - A family with 7 genera in CA. Ceanothus is a large and important genus of shrubs.

  • Ceanothus "California lilac, deer brush"
    Shrubs with evergreen or deciduous leaves. There are two groups of species in CA: 1) those with mostly opposite, evergreen leaves and knobby dark stipule bases that remain on the stems after most of the stipule has fallen off; and 2) those with alternate, deciduous leaves that lack knobby stipule bases. Type #2 has leaves that usually have three main veins from the base. The flowers of Ceanothus are small, but grouped into beautiful showy clusters. They have petals that are ladle-shaped. Are the stamens opposite or alternate the petals? _____________________ There is a nectary disk that surrounds the ovary and sort of buries it, but the ovary of the single pistil is superior.

  • Frangula "coffee berry "
    Evergreen or deciduous shrubs with alternate, pinnately veined leaves that often have very regular, straight secondary veins. The flowers are small and greenish and often lack petals. The stamen/petal arrangement is the same as in Ceanothus and the rest of the Rhamnaceae.



Fabaceae (alternative name Leguminosae based on the fruit type) - one of the largest angiosperm families, very well developed in California, with 55 genera, some with over 50 native species! The unifying feature of the members of this family is the legume fruit, which develops from a single carpel.

Within this family, there are three sub-families, and the key to the genera of the Fabaceae in the Jepson manual divides up the species by sub-family first (see diagrams on next page):

Papilionoideae: Bilateral flowers with the petals arranged into banner (top petal), wings (the two side petals) and keel (the two lowest petals with are connivant into a boat-shaped structure). In bud, the banner encloses all the other petals. Stamens usually 10, sometimes all fused in tube around the pistil, or 9 fused and 1 free. This subfamily contains all but 12 of the CA genera.

Caesalpinoideae: Bilateral flowers with the petals arranged into an upper petal (sometimes called a banner), 2 upper or side lateral petals (sometimes called wings), and two lower petals (not connivant, but forming a keel-like structure in Cercis). In bud, the upper petal is inside all the other petals. Stamens are usually 10, usually free. This subfamily contains 6 of the California genera.

Mimosoideae: Radial flowers with many free, showy stamens. This has the remaining 6 genera.

From Judd et al. (1999)



  • Lupinus (to know genus) "lupine"
    A large genus in CA with some of our most beautiful native wildflowers.
    Annual to perennial herbs or shrubs. Leaves palmately compound, usually with 5-9 leaflets. The flowers are arranged in a raceme; sometimes the flowers are in clear whorls at the nodes of the raceme. Look at the flowers to see how the banner enfolds the other petals in bud.
    Papilionoideae flowers such as these are often pollinated by bees. The bees use the wings as a landing platform on which they stand as they collect nectar from a disk near the base of the ovary. As they reach toward the ovary, they depress the wings and keel and expose the stamens and style so that pollination can occur. Some lupines have a "color change" on their banner after pollination takes place. Bees are smart and learn quickly that only the pre-change flowers have nectar left in them, and the plant makes good use of its pollinators by directing them to flowers that have unpollinated stigmas!

  • Trifolium (to know genus) "clover"
    Another large genus in CA, present in many habitats.
    Annual to perennial herbs. Leaves palmately or pinnately trifoliolate, the leaflets often having serrated edges (trifoliumleafedge). The flowers are often arranged in heads (sometimes elongate and more like a spike) which may or may not have a subtending involucre.

  • Acmispon "trefoil, lotus"
    A genus of native herbs. Leaves are pinnately compound, sometimes with more leaflets on one side of the rachis than the other. The flowers may be solitary or in umbels.

  • Lotus "trefoil, lotus"
    A large genus of herbs native to Europe, Asia, Africa, and Australia, with four species naturalized in California. Leaves are pinnately compound, sometimes with the lowest pair of leaflets in the stipular position. The flowers may be solitary or in umbels.

  • Vicia "vetch"
    We have both native and non-native vines in this genus; note the tendrils at the tips of the compound leaves.


  • Cercis occidentalis (to know genus) "western redbud"
    A genus with one species in CA. These are small trees with entire, cordate, deciduous, palmately veined leaves. The flowers and pods are pink to red. Examine the flowers to see how the upper petal is inside the others in bud.

  • Parkinsonia "palo verde"
    2 native species of desert shrubs with very green stems.


  • Prosopis "mesquite"
    Shrubs of dry or alkaline areas, often in washes; 2 of our species are native and 2 are introduced. Look at the neat coiled pods. Yes, this is where we get mesquite charcoal.

  • Acacia/Vachellia "acacia, wattle"
    Two cultivated genera that have become naturalized in California, sometimes heavily invading native plant communities, especially along roadsides. The seven naturalized species of Acacia are native to Australia; they usually have alternate, evergreen, pinnately compound leaves. Sometimes the leaves appear simple, due to being reduced to only the petiole (or midrib) of the leaf; such reduced leaves are called "phyllodes." The species Vachellia farnesiana is a tree native to tropical America with alternate, bipinnately compound leaves. Note the radial flowers with many colored stamens.



Cucurbitaceae - A very important food family, containing squashes, zucchini, cucumbers, and pumpkins. This is a family of tendril-bearing mostly herbaceous vines that usually have alternate, palmately veined leaves. The flowers are unisexual.

  • Marah "wild cucumber, big-root, manroot"
    A small genus of 5 species in CA. Monoecious, herbaceous vines that arise each year from large tubers - some of the tubers are so large that there is a story about a tuber that had to be dug up with a bulldozer. The interesting flowers are borne in clusters at the leaf axils. The staminate flowers are in racemes; the pistillate flowers are solitary, borne at the base of some of the staminate racemes. If flowers are available, look at the staminate flowers. Are the stamens free or fused? ___________________ If pistillate flowers are available, look at the ovary placement in the single pistil. Is it superior or inferior? ___________________________



In California, these are wind-pollinated, monoecious trees and shrubs:

Fagaceae - Evergreen or deciduous trees or shrubs with alternate leaves Three genera in California. The staminate flowers are borne in catkins. The pistillate flowers are solitary or in small clusters.

  • Quercus "oak"
    Trees or shrubs (sometimes the same species can be a tree or a shrub), the leaves are often lobed or at least bristled or spiny along the margins. The staminate flowers are grouped into very loose, dangling catkins; each staminate flower is subtended by a bract that falls off very early which means that these catkins lack obvious bracts. The pistillate flowers are located further out along the branches than the staminate flowers, and they consist solely of an involucre of bracts and a pistil with three reddish styles. In fruit, the involucre becomes a little cap subtending the fruit (a nut); the nut plus cap is called an acorn.

The oaks in California can be divided up into "red oaks" (some people call them "black oaks" - Q. kelloggii, Q. wislizeni, Q. agrifolia, Q. parvula), "intermediate oaks" (Q. chrysolepis, Q. vaccinifolia, Q. tomentella, and Q. palmeri), and "white oaks" (all the rest of the species except the "intermediate oaks"). The first couplet of the key to oak species in the Jepson Manual separates the "red oaks" from the rest of the species. The red oaks tend to have thin scales on the cap of the acorn and rather dark bark; the white oaks tend to have thick tubercled scales on their caps and light bark.

Examine the species that we have on display. Look for the differences in the scale texture on the acorn caps. Notice, also, differences in leaf shape and nut size. Fill in the chart on the next page.

Oaks that we may have on display:

  • Q. agrifolia "coast live oak"
    Evergreen oak common in mixed evergreen forests of the outer coast ranges. The leaves (11437) are somewhat cupped (the upper side convex), the margins are spiny, and usually have 10 or fewer secondary veins. Look for the hairs in the axils of the secondary veins on the shiny underside of the leaf.

  • Q. wislizeni "interior live oak"
    Evergreen oak that resembles Q. agrifolia but is found in more interior foothill areas of CA. The leaves also have spiny margins, but they are not usually as cupped as in Q. agrifolia, and they usually have more than 10 secondary veins which lack the hairs in the vein axils of the shiny leaf underside.

  • Q. kelloggii "black oak"
    Common in the Sierras in the yellow pine belt. The leaves are deeply lobed, with each lobe ending in a bristle.

  • Q. lobata "valley oak"
    A species that once inhabited extensive riparian woodlands and flood plains of the central valley. The yellow green leaves are deeply lobed, but not spiney.

  • Q. douglasii "blue oak"
    Common tree of savannah (grassland with oaks well spaced) in the foothills ringing the Central Valley. The foliage is glaucous and has a blue-green color. The leaves are shallowly lobed and not spiny.

  • Q. chrysolepis "canyon live oak"
    Found on exposed slopes of the sides of canyons. It can range from a bush to a tree. The leaves are very variable, even on the same plant, the margins ranging from entire to highly lobed and spiny. The leaves have a pale gray-green underside that is covered with golden hairs when young.

  • Q. berberidifolia "scrub oak"
    Shrub found in many communities in CA. The leaves look like a hybrid between those of Q. wislizini and Q. douglasii. The top side of the leaf is shiny, not glaucous, the bottom side is glaucous, and each lobe usually ends in a spine.

Non-Quercus species:

  • Notholithocarpus densiflorus "tanbark oak"
    This evergreen species has two wide-ranging varieties. It can range from a tall tree to a shrub and is an important dominant in mixed evergreen forest as well as mixed conifer forest (after a fire, the shrub form can form almost pure stands in the Sierra Nevada). The leaves have prominent veins and the margins are spiny. The staminate catkins in this species are erect and stiff. The pistillate flowers are in small clusters, subtended by an involucre. In fruit, the acorn has a cap with long, reflexed (curled) scales.

  • Chrysolepis "golden chinquapin"
    An evergreen shrub with golden powdery scales covering the leaves and stems. The staminate catkin is erect; the pistillate flowers are enclosed in a spiny bur.


Betulaceae - Deciduous trees or shrubs of moist areas (often riparian woodlands in CA) with alternate leaves with strong straight veins and margins that are often doubly serrated (the serrations are serrated). Both the staminate and pistillate flowers are arranged in bracteate catkins and, unlike in the Fagaceae, the bracts are quite obvious.

  • Alnus "alder"
    Trees or shrubs with smooth grayish bark. The staminate catkins are elongated and flexible and fall from the tree after releasing the pollen. The pistillate catkins are ovoid and have bracts that become woody with age and remain on the tree. The fruit is a nutlet that falls from the woody pistillate catkin bracts.

  • Corylus cornuta "California hazelnut"
    Small tree or shrub with alternate, deciduous, soft-hairy leaves. The staminate catkins are pendant. The pistillate flowers are in a small cluster, and each flower is surrounded by an involucre that matures into a husk that surrounds a nut.


Juglandaceae - a family with two native species in CA.

  • Juglans "walnut"
    Deciduous trees with alternate, odd-pinnate once compound leaves. The staminate flowers are in long flexible dangling catkins without obvious bracts (the sepals are fused to a bract). The pistillate flowers are in small clusters with each flower subtended by an involucre. The fruit is a nut that is covered by a husk that is derived from the involucre.



Cornaceae - A family with one genus in CA.

  • Cornus "dogwood"
    Shrubs or trees with opposite, deciduous leaves, the leaves often with secondary veins that curve up toward the leaf tips (arcuate venation). Have your T.A. demonstrate the "dogwood test" where you tear the leaf but it stays connected by the vascular bundles of the veins - the vascular tissue is very strong in this genus, due to the spiral thickenings of the vessels. The stems are usually smooth, but they have a jointed look at the nodes, due to distinctive bud scars. The flowers are small and usually 4-merous, arranged in clusters that appear umbel-like or head-like; the inflorescence is sometimes surrounded by rather showy petal-like bracts. The pistil of each flower has an inferior ovary that develops into a drupe.


Hydrangeaceae - A family of woody plants with opposite leaves. There are five genera in CA.

  • Carpenteria californica "tree anemone"
    This is a genus of one species which is a rare shrub of the southern Sierra Nevada (this specimen is from the arboretum - it does well in cultivation). The leaves are simple, evergreen, and leathery. The flowers are large and showy with white petals and many stamens which may be in clusters. Is the ovary of the pistil inferior or superior? ___________________ How many styles are there? _____

  • Whipplea modesta "yerba de selva"
    A genus with one species in CA. A low-growing shrub (subshrub) with evergreen leaves that is found in the coast range in coniferous forests. The small flowers are arranged in a dense cluster and have white petals. Note the ovary placement in this species (the Jepson Manual calls it ½-inferior).


Ericales (part 1)

Polemoniaceae - A family with beautiful (although sometimes small) flowers. There are 17 genera in California; all the species are native. How many carpels do members of this family have? _______
What stigma characteristic usually helps you recognize this family? ___________ Many of the genera have an interesting calyx with translucent membranes connecting the calyx lobes into a tube.
This family is often used as an example of adaptive radiation in the angiosperms, because there is such a range of corolla color and size that has evolved in response to different pollinators (hummingbirds, butterflies, bees, flies). Look at the color xeroxes of different flower types that we have provided.

  • Leptosiphon
    Small herbs with opposite leaves. The leaves can be entire or palmately lobed (sometimes deeply so); the deeply lobed opposite leaves may resemble a whorl of leaves. The flowers are typical of the Polemoniaceae, as described above, there is usually a long corolla tube, and the pollen is always yellow.

  • Gilia
    Herbs, often small, but sometimes large and showy. The leaves are alternate, entire to pinnately lobed; in one group of species, the leaves are mostly basal. The stems or other parts of the plant sometimes have cobwebby hairs or glandular hairs. The flowers are similar to those of Leptosiphon, but the pollen can be blue.

  • Navarretia
    Small annual herbs with alternate, usually deeply pinnately lobed leaves. The flowers are arranged into heads that are subtended by bracts that are usually spine-tipped. Some species in this genus have flowers with two stigma lobes rather than three.


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