lab manual

 

<< Lab 5 Asterids: Ericales (Ericaceae); Asterids I: Garryales (Garryaceae); Gentianales (Rubiaceae, Apocynaceae); Boraginaceae; Solanales (Solanaceae, Convolvulaceae); Lamiales (Lamiaceae, Orobanchaceae, Phrymaceae, Plantaginaceae) >>

 

Ericales (part 2)

Ericaceae - A family of cooler regions (ie. the temperate zone or high elevations), often found on acidic soils.  There are 26 genera in California with tremendous variability in life form. The genera range from trees such as Arbutus to shrubs and herbs. Blueberries, cranberries, and huckleberries are all in the genus Vaccinium.

The first couplet in the key to the genera of the Ericaceae divides the non-photosynthetic taxa from the photosynthetic ones.  This is because a number of the genera lack chlorophyll and obtain all of their food and nutrients via a connection to a fungus.  The fungal associate obtains nutrients either by attaching itself to the roots of another plant or by digesting dead plant material, such as decaying leaves.  Therefore, the ericaceous plants that have fungal associates that are attached to the roots of other plants are mycoparasites, ie. they indirectly parasitize (via a fungus) other angiosperm species.

Despite the variability in habit and life-style among the genera of the Ericaceae, all members have the following combination of characters:  petals connate and stamens twice as many as corolla lobes and generally free of the corolla.  Many of the genera have corollas that are "urceolate" - urn shaped.  The anthers often dehisce by pores.

  • Arctostaphylos "manzanita"
    A large genus of shrubs (ca. 62 species) that are an important component of our chaparral and scrub vegetation types in California. They are often fire-adapted, either in terms of seed germination or ability to resprout after a fire. Some of the species have a "burl" - a thickened basal area on the stem - from which they resprout. The bark is usually a smooth reddish-brown, and sometimes, it peels off in strips. The alternate leaves are evergreen and often ovate and glaucous. The flowers are urn-shaped. The ovary of the single pistil is superior. The stamens have anthers that dehisce by pores, but the anthers hang upside-down so that it is the base of the anthers that dehisce upwards. Notice the awns on the anthers. How do you think bees get the pollen out of the anthers of manzanitas? ________________________________________________

  • Arbutus menziesii "madrone"
    Trees of mixed evergreen forests that have rather sinuous trunks and smooth reddish-brown bark that peels off in strips. The alternate, evergreen leaves are larger than those found in manzanitas and are shiny on the upperside. The flowers are similar to those in manzanita, but the corollas are larger, and at the base of the corolla there are little see-through windows.

  • Rhododendron occidentale  "western azalea"
    Shrubs of cooler regions of California (coastal or higher elevation). The alternate leaves are deciduous.  How does the corolla of this genus differ from that of Arctostaphylos? ________________________________________________________

  • Vaccinium ovatum "huckleberry"
    Shrubs of cooler areas, often found near the coast (coastal scrub vegetation), although there are inland populations too. The leaves are alternate and may be evergreen or deciduous. The urn-shaped flowers are 4-5 merous. Is the ovary superior or inferior? _____________

  • Gaultheria shallon "salal"
    A low shrub of coastal areas with evergreen leaves that are widely ovate and may be sharp-pointed. The flowers are pink and urn-shaped. Look at the leaves. How does the leaf margin of these leaves differ from that of Arctostaphylos? _______________________________

 

The rest of today’s lab is devoted to families in orders belonging to the Asterid I clade. The first family is rather uncharacteristic, consisting of wind-pollinated woody plants whose flowers are borne in catkins.

Garryales

Garryaceae - A small family composed of two genera, only one of which is in the Jepson Manual. (The other genus in the family, Aucuba, is fairly common in CA as a shade-tolerant landscaping plant).

  • Garrya "silk tassel"
    Small, dioecious trees or shrubs with opposite, leathery, evergreen leaves with entire margins. The flowers are in catkins that have bracts that are opposite and decussate (the pairs are placed at 90 degree angles to oneanother), making the catkins 4-ranked (when examined from the top, the bracts emerge on four sides). The staminate catkins are quite flexible and dangle in the wind; the pistillate catkins are more tightly arranged.  The staminate flowers are 4-merous; the pistillate flowers lack perianth and have an inferior ovary. How would you distinguish this family from the Betulaceae and the Fagaceae? _____________________

 

The rest of the dicotyledon families that we will look at will have more typical Asterid flowers, having corollas with connate petals and stamens adnate to the corolla; all but one (Rubiaceae) have superior ovaries.

Gentianales

Apocynaceae - There are 10 genera in CA, four of which include only non-native species. In California, the Apocynaceae consists of perennial herbs and shrubs with milky sap.  The leaves are often opposite, but not always.  The corolla of the flowers often has a distinctive pin-wheel look to it, in that the corolla lobes overlap on one side or are bent to one side .  The anthers often closely surround the gynoecium, and the stigma is often large. Members of the genera formerly treated under Asclepiadaceae (e.g., Asclepias, “milkweeds”) have highly modified flowers in which the androecium is fused to the gynoecium and the pollen is aggregated in structures called "pollinia."

Members of this family have a distinctive gynoecium where the two carpels are free at the level of the ovary but fused from the styles up.  In some genera, the ovaries from both carpels mature into follicles, while in others (formerly treated under Asclepiadaceae), only one carpel matures.  The seeds often have tufts of silky hairs.  How do you think these seeds are dispersed? ________________________

  • Apocynum "indian hemp, dogbane"
    We usually have Apocynum cannibinum for you to examine, but it isn't always fertile.  This interesting species is becoming rather hard to find in California.  Native Californians use the outer part of the stem as a source of fiber.  The leaves are opposite and the flowers are small and bell-shaped.  If we have fertile material, note that the lobes of the corolla overlap on one side, and the arrow-shaped anthers come together in a pointy cone that covers the rather fat stigma.

  • Vinca "periwinkle"
    This is a non-native genus, escaped from people's gardens where it is used as a ground cover.  The leaves are opposite, shiny, and glabrous.  The corollas on this plant show the pinwheel shape that I mentioned above.  Look at the arrangement of the stamens around the gynoecium and the enlarged stigma.  Look, also, at the two-parted ovary.  Break off a piece of this plant.  What color is the sap? _________________

  • Nerium oleander "oleander"
    A commonly planted shrub. All parts are poisonous. The flowers are very typical of the family. What is the phyllotaxis? ________________________

  • Aclepias "milkweed"
    In California, these are mostly perennial herbs; two species get shrubby. The leaves are usually opposite or whorled, but they are alternate in a few species. The flowers are clustered into an umbel-like inflorescence and the corollas range in color from greenish to purple and orange. Examine the reflexed sepals and petals. How many are there? _____________________

    Internal to the petals is the highly modified androecium. The filaments are fused around the gynoecium and bear hoods and sometimes, within the hoods, horns (look at the diagram). Internal to the hood structures are the anthers which each have two pollen sacs or pollinia. Interestingly, the left pollen sac of one anther is connected to the right pollen sac of the adjacent anther via a "connective" and "gland" (see diagram). When a bee or butterfly visits these flowers, their legs get tangled up in the gland and they carry off the pollinia on their legs. See if you can pluck off a pair of pollinia by inserting your needle under the gland.
    Internal to the androecium is the gynoecium with its two-parted ovary, style, and enlarged stigmatic head. The top of the stigmatic head is not receptive. Pollinators come to the plant carrying pollinia on their legs, and the pollinia have to slip into special stigmatic crevices on the side of the head. Whew! Who figured out this one! Good luck with your dissection!

 

Rubiaceae -  A mostly tropical family.  We have seven genera, four of which are entirely non-native.  The genus Galium is relatively large and common.  Plants in this family are distinguished by their opposite leaves and well-developed stipules that run between the leaf petioles (interpetiolar stipules).  The flowers have an inferior ovary.

  • Galium "bedstraw, cleavers"
    Annual or perennial herbs that may become somewhat woody.  The leaves are actually opposite, but they appear whorled due to development of the interpetiolar stipules.  The flowers are tiny and 4-merous.  Some species are dioecious.  The most common species is Galium aparine.  Take a piece of the stem and stick it to your clothes. Why does it stick so well? ___________________ Look at the developing fruits; how many carpels per fruit/ovary are there? ________ Is the ovary superior or inferior? ______________

 

The next family is not currently classified in any order:

Boraginaceae - This is a common family in California, with 31 genera, several of which are quite large. In CA these are mostly herbs.  An important feature of the family is its inflorescence type, a one-sided cyme, sometimes called a helicoid (or scorpioid) cyme, which is very obvious in some genera but less so in others, and lacking entirely in some species.

This is another family whose circumscription has been broadened based on results of molecular phylogenetic studies. The first couplet in the key to genera in the second edition of The Jepson Manual separates the parasitic genus Pholisma, which was formerly classified in Lennoaceae and includes two species native to dunes and deserts in southern California, Arizona, and northern Mexico, from the rest of the family. The next couplet separates the genera with deeply 4-lobed ovaries and gynobasic styles, which have always been classified in Boraginaceae, from those with entire ovaries, which were formerly classified in “Hydrophyllaceae.” In the first group, the individual segments of the ovary mature separately into "nutlets"; in some cases, not all segments reach maturity. In the second group, the fruit is a capsule.

Beginning keyers often fear this family, because many of the genera in the group with lobed ovaries are separated by minute characters such as shape of receptacle and nutlet ornamentation.  It is sometimes hard to key members of this family without mature nutlets.  If you look in the oldest flowers toward the base of the cyme (where the corollas have fallen off) and you look inside the calyx, that is where you will find the most mature nutlets.  Even if you don't have mature nutlets, you can make an educated guess about some of the features.  For example, some genera have flat receptacles with the ovary segments attached at their bases Other genera have conic receptacles, which means that the ovary segments are attached laterally.  This feature can be seen without mature nutlets. In addition, the ornamentation of the nutlets can sometimes be guessed at based on the ornamentation of the developing ovary.

Another striking feature of many members of the lobed-ovary group in this family is the "corona," which is a ring of pillowy appendages at the throat of the corolla (in Jepson it's just called appendages).  Not all species have this ring, but when it is present, it is often colored differently than the rest of the corolla.  If you look carefully at some corona-bearing flowers you may see that the corona changes color with age.  Some begin yellow and fade to white; others begin white and fade to blue.  This is called a "color-change", and it is a signal to the pollinator telling them which flowers no longer have nectar (and are already pollinated).  Thus, smart pollinators only visit the pre-change flowers.

  • Amsinckia "fiddleneck"
    Annuals - very common. The corollas are orange or yellow and lack a corona. Notice the texture of the hairs which is described as "bristly" in the Jepson manual. In this genus, is the receptacle conic or flat? _________________________

  • Plagiobothrys or Cryptantha "popcorn flower"
    These two genera of herbs usually have white corollas and are easily confused. Technically, only Plagiobothrys species are called "popcorn flower." These are small annuals or perennials. In both genera, the attachment of the nutlets is usually lateral, but sometimes basal. To distinguish the two genera, nearly ripe nutlets are important, because one has to examine the scar on the nutlet where it was attached to the receptacle (looking at the pictures of the two types of nutlet scars is helpful). In some Cryptantha species, only one nutlet matures, whereas in Plagiobothrys usually all four nutlets mature.

  • Cynoglossum "hound's tongue"
    Perennial or biennial herbs with large, tongue-shaped, basal leaves and blue corollas. The corolla has a large white "corona." The lobed ovary develops into nutlets that spread out in fruit (like petals opening) and are covered with barbed prickles.

  • Myosotis "forget-me-not"
    Most of our species in this genus of herbs are non-native. They somewhat resemble the species of Cynoglossum in that most Myosotis species have a blue corolla and white pronounced corona, however they lack large basal leaves. Is the receptacle in this genus flat or conic? ________________________________

  • Eriodictyon "yerba santa"
    Shrubs with white to purple corollas. We usually have the locally common species Eriodictyon californicum which has sticky-glandular leaves and white flowers.  The scorpioid cyme inflorescence isn't as coiled as in some other members of this family.

  • Phacelia A large genus of herbs (94 species in CA - all native).
    The leaves can be simple or pinnately lobed or compound. The flowers have rotate (plate-like) to bell-shaped corollas and are in a very tightly coiled scorpioid cyme. This is another genus with a bad reputation for being hard to key out. Some of the species look very similar and one has to count ovules or seeds to sort them out! How many styles are there? ________________ Are there style branches? __________________

  • Nemophila "baby blue eyes, fivespot"
    Annual herbs, with pinnately toothed or lobed leaves, and flowers borne singly in the leaf axils (not in scorpioid cymes). The corolla is rotate to bell-shaped and often has contrasting colors or spots.

 

Solanales

Solanaceae - This Asterid family doesn't really have many distinguishing features.  If you see a plant in California that isn't a vine, has alternate leaves, has clear sap, and has the following floral features: bisexual flowers, connate petals, stamens adnate to the corolla, stamens as many as and alternate with the petal lobes, a conic (unlobed) superior ovary, one unbranched style, and inflorescences that aren't scorpioid cymes, then think Solanaceae.  The family is recognizable by not having any distinguishing characteristics.  We have a number of non-native species in this family, some of which are noxious weeds.

  • Solanum "nightshade"
    This genus is one of the largest genera of flowering plants, having over 1,500 species.  From this one genus, we get tomatoes, potatoes, and eggplants.  In the tropics, where the genus is best developed, it can be of variable habit (including vines), but in California we have herbs and shrubs.  We have a number of beautiful native species, but also have many non-natives in CA, some of which are prickly.  The corollas are often rotate (plate-like).  Sometimes the anthers dehisce by slits, but more often by pores. In the sample that you have, how do the anthers dehisce? ________________ The fruit is a berry. The leaves and unripe fruits of many species are poisonous, when eaten.

  • Nicotiana "tobacco"
    We have both native and introduced species in this genus.  Usually in lab, we have the non-native Nicotiana glauca ("tree tobacco") which is very common in the coast ranges.  In CA, we have mostly herbs (the exception is tree tobacco). The leaves have a strong smell to them; sometimes the plants are quite glandular. The flowers have a corolla with a long tube and small to large limb; what is the symmetry of the corolla? _____________________

  • Datura "jimson weed"
    Again, we have both native and introduced species in this genus which is famous for its hallucinogenic properties. The large, white corolla is trumpet-shaped. To show you what this genus looks like, we may have the flowers of Brugmansia on display - the flowers of this genus are very similar to those of Datura (they were once in the same genus).

 

Convolvulaceae - A family that somewhat resembles the Solanaceae, but all the California species are twining or trailing vines, some with milky sap. One genus, Cuscuta (dodder) includes parasitic vines that have no or highly reduced leaves and lack chlorophyll; they obtain nutrients via specialized roots that penetrate the host plant tissues.  The other members of the family have alternate leaves and often quite showy flowers. The corolla is twisted in bud. Why is one of the common names for this family the "morning-glory" family? ...... (it has to do with the flowers)

  • Convolvulus "bindweed, morning-glory"
    We often have C. arvensis (field bind-weed), a common weed with white flowers.  How would you describe the leaf shape? _________________  How would you tell this species from the other twining vines that we have seen in lab? ____________________ __________________________________ __________________________________________

  • Calystegia "morning-glory"
    Our native "morning glory" has much larger flowers (and longer calyces) than our non-native morning glories.

 

Lamiales

Many members of this order have bilabiate (2-lipped) corollas – a type of bilateral symmetry in which the five petals are fused into a tube and the lobes are arranged into two lips – with two lobes up and three lobes down. These flowers typically have just 4 epipetalous stamens, sometimes only 2, and sometimes the fifth stamen is represented by a staminode (sterile stamen).

Lamiaceae - The mint family - another family with an alternate name, Labiatae. This family is easily recognized by its stems, which are usually square in cross section, opposite leaves (which are often fragrant), and bilateral flowers, usually with 4 stamens (sometimes 2). The ovary is deeply 4-lobed and the style is usually gynobasic; the fruits are four nutlets. (Where have we seen this combination of characters before?) The family is well-developed in CA, with 27 genera, most of which are native.

  • Salvia "sage"
    A popular genus with gardeners. This genus of herbs and shrubs is recognized partly by the number of fertile stamens; how many are there? ________
    How are the anther sacs attached to the filament? __________________________________________
    Smell the fragrance of the leaves.

  • Marrubium vulgare "horehound"
    An introduced genus of perennial herbs with one species in CA. Notice the gray-green color of the foliage. How would you describe the inflorescence? ___________
    How many fertile stamens does this species have? _________
    Is the fragrance of this species as pleasant as sage? ____________

  • Trichostema "blue curls"
    This is a cultivated form from the arboretum. Notice the corolla in this genus of herbs and shrubs. How would you describe it? Is it two lipped or is it lacking a lip? ______________________________ Notice the long stamens. The fragrance of these plants is often strong (one of them is called "turpentine weed" and another "vinegar weed").

  • Lepechinia calycina "pitcher sage"
    This is a common native shrub in the foothills. A distinctive feature of this genus is that the calyx inflates in fruit. How many fertile stamens are there? ________

  • Stachys "hedge nettle"
    This species of this genus of herbs resemble "stinging nettle" to some extent, but they have no stinging hairs. The scent of the leaves is musty.

 

Orobanchaceae - This family includes fully parasitic plants (holoparasites), represented in California by species in two genera (Kopsiopsis and Orobanche), as well as hemiparasites formerly classified in “Scrophulariaceae,” represented by nine genera in CA. They all have strongly bilaterally symmetrical (bilabiate) corollas and usually 4 stamens.

  • Castilleja / Triphysaria / Orthocarpus / Cordylanthus "Indian paintbrush, owl's-clover, butter and eggs, bird's beak"
    Four genera of hemi-parasitic herbs and subshrubs. Consult the diagrams from a paper that was published in 1991 which is the basis for the treatment of these genera in the Jepson Manual. In all of these genera, the inflorescence is spike-like (or a panicle of spikes) and the inflorescence bracts may be highly colored (pink, yellow, crimson, red....even white).

    In Castilleja, the upper lip of the corolla is a short to long beak or "galea", and it is supposed to be open at the tip (but it is hooked closed in some species). The lower lip ranges from very reduced with 3 small lobes to deeply 3-pouched. There are two anther sacs per stamen, inserted at different levels on the filament. The stigma is usually expanded into a small flattened or lobed ball.

    In Triphysaria, the upper lip of the corolla is a short beak, slightly longer than the lower lip, and it is supposed to be open at the tip. The lower lip is deeply 3-pouched. There is only one anther sac per stamen (an excellent diagnostic feature that is sometimes hard to see). The stigma is usually expanded into a small flattened ball, as in Castilleja.

    In Orthocarpus, the upper lip of the corolla is a short beak, similar to that of Triphysaria, and it is supposed to be closed at the tip. The lower lip is 3-pouched. The stamens are the same as in Castilleja. The stigma is unexpanded (it looks like there isn't a stigma at the end of the style).

    In Cordylanthus, the upper lip of the corolla is a short beak about equal to the lower lip, which is 3-pouched, and the beak is supposed to be closed at the tip. The stamens are the same as in Castilleja. The stigma is the same as in Orthocarpus. The calyx in this genus is different than in the other three, because it is "sheath-like", wrapped around the corolla like a blanket, open all the way to the base on one side. In the other three genera, the calyx can be deeply lobed on four sides, but usually not to the base.

 

Phrymaceae - This small family is important for us because it includes the large, diverse genus Mimulus, formerly classified in “Scrophulariaceae.” These are herbs and shrubs with opposite simple leaves. The sepals are fused and the calyx tube is ribbed and pleated; the corolla is bilabiate, there are 4 stamens in two pairs, and the stigma is 2-lobed.

  • Mimulus "monkey flower"
    The lower corolla lip usually has two prominent longitudinal folds. The two stigma lobes are large. What happens when the stigma is touched? ______________________________________ Are there staminodes in these flowers? ______

 

Plantaginaceae - Based on molecular phylogenetic evidence, this family is now circumscribed much more broadly than in the past (26 genera in the second edition of The Jepson Manual vs. one in the first edition) and includes many genera previously classified in “Scrophulariaceae” (in California, exceptions include Scrophularia and Verbascum, which are both still treated in Scrophulariaceae) and aquatics fromerly classified in Callitrichaceae and Hippuridaceae, as well as the wind-pollinated herbs in the genus Plantago. In most members of the family, as in the Lamiaceae, the corolla of the flowers is bilaterally symmetrical and bilabiate and the stamen number is usually 4 (or 2); sometimes there is a fifth stamen that is reduced to a staminode.

  • Collinsia "Chinese houses"
    Annual herbs with opposite leaves and corollas superficially like those in Fabaceae subfamily Papilionoideae. The upper lip looks like a banner, and the lower lip looks like two wings and a keel. What non-fruit characteristics could you use to tell that this genus is not in the Fabaceae? __________________

  • Penstemon "beardtongue"
    Herbs and shrubs, usually with opposite leaves, and often with showy flowers. There is a prominent staminode in these flowers, which is usually hairy, thus the name "beardtongue".

  • Digitalis "foxglove"
    A non-native with showy flowers that has escaped in some areas of California (common near Pt. Reyes). The plant is poisonous if eaten, but it is used medicinally for heart problems.

  • Plantago "plantain"
    Herbs with leaves in a basal rosette and scapose inflorescences. Flowers small with 4-merous scarious corolla which may be radially or bilaterally symmetrical. We have 15 species in California, and half of them are non-native. The two most common non-natives, P. lanceolata and P. major, are very common weeds. Look at the spike inflorescences. Can you see the styles and stamens exerted from the flowers at the same level of the inflorescence? _____ Where in the inflorescence do you see the styles exerted? ____ Where do you see the stamens? ______ What is the significance of your observations? ___________________________

 

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