5/2/16
Week 5; Monday
Announcements: Exam results: acknowledge top students. - Field trip two Saturdays away; will have sign-up sheets in lab this week. - quiz in lab on Wednesday - keying (15 pts) and family ID (20 pts)
Lecture: Rosidae s.l. continued: Last two families are pretty closely related, even though they may seem rather different. They form an interesting contrast. In one, Rosaceae, the flowers are all pretty much alike, but fruit types differ greatly and form the basis of subfamilial divisions, whereas in the other, Fabaceae, fruit types are all similar - the legume - but flowers differ greatly and form the basis of subfamilies.
Rosaceae - Rose family (95 gen/2825 spp) 1) plants woody or herbaceous 2) leaves simple or compound (palmate or more commonly pinnate) - stipules present - leaves/leaflets with serrate margins - alternate arrangement 3) Flowers - actinomorphic - sepals and petals in 5s - stamens many - Hypanthium usually present - ovary superior, inferior, or half inferior - carpel number variation 1, 5, or many – traditional subfam. characters
Most striking variation in reproductive morphology is in fruit type.
Traditional view of divisions within family: Subfamilies are based on fruit type Chromosome number correlates somewhat but is more variable
Subfamilies: fruit type chromosome number Spiraeoideae: * 5, 5, ∞, 5 follicle, capsule [carpels usually free] x = 8, 9
Rosoideae: * 5, 5, ∞, ∞ achene, drupelet [carpels always free] x = 7, 9
Prunoideae: * 5, 5, ∞, 1 drupe (some seeds contain cyanide) x = 8 __ Pomoideae: * 5, 5, ∞, 5 Pome [carpels fused] x = 16, 17
Page 38
5/2/16
However, recent studies have shown that some of the subfamilies based on fruit type are not all monophyletic and that chromosome number is a better indication of phylogeny see overhead
Phylogeny: Subfamilies Prunoideae and Pomoideae (Maloideae) are monophyletic, whereas Rosoideae are polyphyletic, and Spiraeoideae are probably the ancestral paraphyletic group in the Rosaceae.
Ed Abbey – Cliffrose from A Desert Solitaire
Fabaceae (Leguminosae) - Pea or legume family (642 gen/18,000 spp) 1) mostly woody tropical trees, but in temperate zone mostly herbs 2) many with alkaloids (subfam. Papilionoideae) 3) Commonly associated with N-fixing bacteria as symbionts in roots (Rhizobium) 4) Leaves compound - stipules present - margins entire - alternate arrangement 5) Flowers – three basic floral types - zygomorphic (2 types) or actinomorphic (1 type) - sepals and petals in 5s - stamens: - 10 unfused – subfam. Caesalpinoideae - 10 partly fused – diadelphous (9 fused and 1 free) subfam. Papilionoideae - many – subfam. Mimosoideae - ovary superior - fruit a legume (specific type of follicle)
The two zygomorphic floral types are called “Flag” flowers; in Papilionoideae the two lower petals are fused to form a “keel”
Banner 1 free stamen Flag Flower wing wing 9 fused stamens keel Papilioniod type flower
Caesalpinoid flowers also often are ‘flag’ flowers, but the lower petals are NOT fused and the stamens are NOT fused. However, sometimes they don’t have a ‘flag’ form
Mimosoid flowers are called “brush” flowers, because they have many stamens that are exerted on long filaments and form a brush that covers visiting insects or birds with pollen. Page 39
5/2/16
In contrast to the Rosaceae, major variation is in floral morphology, while fruit type is constant:
Subfamily fruit flower type Mono/Para? Mimosoideae: * 5, 5, ∞, 1 legume “Brush” flowers Monophyletic Caesalpinoideae: X 5, 5, 10, 1 legume “Flag” flowers Paraphyletic Papilionoideae: X 5, 5, 9 + 1, 1 legume “Flag” flowers Monophyletic
Phylogeny: Subfamily Caesalpinoideae is ancestral (paraphyletic) within the Fabaceae and subfamilies Mimosoideae and Papilionoideae are monophyletic and are derived from Caesalpinoid ancestors.
Page 40
5/2/16
Week 5; Wednesday
Lecture: Caryophyllids – One of the major groups of ‘core Tricolpates’ (along with Rosidae and Asteridae)
Most families belong to the order Caryophyllales, but there are a few additional families in the Caryophyllids, including Polygonaceae (Polygonales) Names of these groups have changed between 2nd and 3rd Ed of Judd [overheads]
Technical Features of the Caryophyllales This group is a well-defined group with some distinctive characters.
1) Free-central to Basal Placentation (hence the archaic name ‘Centrospermae’) -sometimes parietal (e.g., Cactaceae) the breakdown of septa separating locules can go either way to parietal or free- central. REVIEW: If carpels are fused, how do you know the number of carpels? 1) count stigma lobes 2) count number of locules or placental attachment points
2) Betalain pigments - Nitrogen containing red pigments - most other flowering plants have Anthocyanin red pigments. Exception Caryophyllaceae
3) Perisperm nutritive tissue in seeds - derived from ovule wall, rather than from endosperm, therefore is diploid sporophyte parent tissue
5) “P-type plastid” - Unique sieve-tube plastid with filaments and a proteinaceous inclusion. (remember sieve tubes in phloem? An angiosperm synapomorphy)
6) Anomalous secondary growth produced by successive vascular cambia forming outside the phloem this causes the ‘rings’ in beets.
7) Single whorl of tepals (but see comments with various families). - Some anatomists interpret the flowers in the Caryophyllales to be without petals and consider all perianth parts to be tepals, modified bracts (sepals in Portulacaceae), or modified stamens (petals in Caryophyllaceae).
Halophytes (e.g., Chenopodiaceae) and Xerophytes (e.g., Cactaceae) are common in this subclass hence a lot of plants are succulent, which is an adaptation for conserving water
Page 41
5/2/16
The first three families are Caryophyllales:
Caryophyllaceae - Carnation, Pink family (70 gen/2200 spp)
1) Repeat after me: opposite leaves, swollen nodes 2) herbaceous 3) floral parts in 5s - petals often with well developed claw (forming tube) and blade (stamens?) - 5 or 10 stamens - ovary of 2-5 fused carpels, superior; fruit a capsule - placentation usually free-central (basal, axile) 4) NO BETALAINS Floral formula: * 5, ‘5’, 10, 2-5 capsule [carpels fused; superior ovary] ^ interpreted to be modified stamens when present!
Cactaceae - Cactus family (93 gen/1400 spp)
1) habit: succulent stems, variously shaped, sometimes flattened - Primitive cacti are vines or shrubs, have ‘normal’ leaves, and are not succulent. 2) leaves are ephemeral or reduced axillary buds, called areoles, with leaves in the form of spines: glochidia. 3) Flowers exhibit a secondary increase in the number of parts - many tepals usually united at the base into a hypanthium - many stamens arising from the hypanthium - inferior ovary of 3-∞ fused carpels; placentation parietal; fruit a berry 4) BETALAINS
Floral formula: * Te ∞, A ∞, G 3-∞ berry [carpels fused; inferior ovary]
Page 42
5/2/16
Montiaceae – Spring beauty family (14 gen/225 spp.)
Montiaceae always has been included in the paraphyletic family “Portulacaceae,” but this group recently has been divided into several small families. All members of “Portulacaceae” native to the Pacific Northwest belong to Montiaceae “Portulacaceae” was paraphyletic with respect to the Cactaceae (i.e., Cactaceae are derived from within “Portulacaceae”). [overheads of phylogeny and new classification]
1) herbs, plants often somewhat succulent; plants always glabrous 2) BETALAINS 3) lvs simple, alternate, opposite, or basal; often fleshy (almost succulent) 4) flowers - Characteristic paired bracteoles, usually called sepals, beneath each flower - petals (really tepals, because ‘sepals’ are really bracts) – 5 (4-10) - stamens 5 (4 to many) - Lewisia is an important exception here in PNW with many (2-9) sepaloid bracts, many tepals, and often many stamens. 2-3 (-8) fused carpels; ovary superior; free-central to basal placentation; fruit a capsule
Floral formula: * ‘2’, 5(∞), (2)5-∞, 2-3 capsule [carpels fused; superior ovary] ^ interpreted to be bracts.
The last family is in the Polygonales, which is sister to the Caryophyllales
Polygonaceae - Buckwheat family (buckwheat, rhubarb) (43 gen/1100 spp)
1) Herbaceous or woody (woody species mostly in the tropics) 2) lvs simple alternate; with sheathing leaf base derived from the stipules; called an ocrea 3) Flowers 3-parted - tepals usually 6 (sometimes 5) - stamens 6-9 - 2-3 fused carpels, superior ovary, basal placentation - fruit achene or nutlet, often 3-angled or winged 4) NO BETALAINS
Floral formula: * Te 6 (3+3), A 6-9, G (2-)3 nutlet or achene [carpels fused; superior ovary]
Page 43
5/2/16
Week 5; Friday Announcements: Field trip next Saturday. Plan for this if you can go. Sign up in lab next week. Meet at Kincaid loading area at 7:30 for 7:45 departure.
Lecture: Pollination biology - film by Bastian Meeuse.
Handout covers important information for exam.
“Sexual Encounters of the Floral Kind” Handout to accompany film -- Botany 113
Pollination syndromes
Wind Pollination: 1) flowers appear before leaves are out 2) large number of flowers (especially males), often in catkins 3) individual flowers small and inconspicuous - without parts for attraction 4) Big stamens produce lots of pollen 5) Stigmas large and plumose or roughened (papillate) to catch pollen 6) Ratio of pollen to ovules VERY HIGH (up to 6,000 to 1) 7) Plants often with separate staminate and pistillate flowers (monoecious or dioecious)
Many different kinds of insects function as pollinators; often these involve very different floral characteristics: Bees, butterflies, etc.: 1) flowers showy, with brightly colored petals 2) flowers usually with some food reward, two common ones are: pollen - protein rich reward nectar - rich in nutrients (e.g., amino acids and sugars) 3) flowers often with strong favorable scent during the day 4) flowers often with ultraviolet markings visible only to the insects (not to humans)
Moths: 1) flowers often white 2) flowers open and scent released in the evening or at night 3) nectar reward 4) flowers often long and tubular to limit access only to long tongued moths
Carrion flies (Blowflies): 1) flowers purple or brown or greenish-brown 2) flowers often close to the ground 3) scent strong and foul (like dead animal)
“Buzz” pollination by bees: 1) no nectar reward (pollen sole reward) 2) connivent anthers (anthers held together) at center of flower 3) anthers opening by terminal pores; pollen shakes out when the bee buzzes the flower Page 44
5/2/16
Birds often pollinate flowers, too: Hummingbirds (found in North and South America only): 1) flowers with long tubular corollas 2) flowers usually red 3) nectar reward in large quantity, rich in sugars (few other nutrients) 4) flowers often dangle away from plant so that bird can reach it while hovering
In other parts of the world different birds, including Honeycreepers (Hawaii), Honeyeaters (Australia) and Sunbirds (S. Africa) act as pollinators. Flowers adapted to these birds differ from those adapted for hummingbirds by having a “landing platform” for the birds to perch on, because they cannot hover. The flowers still have long tubular corollas and lots of sugar- rich nectar.
POLLINATION BIOLOGY – STUDY QUESTIONS
Pollinator specificity • How likely are the hammer orchid (Drakaea) and bucket orchid (Coryanthes) to be pollinated by anything other than their wasp/bee?
• What do you think the pollen:ovule ratio is like in these orchids?
• How is this different to wind pollinated plants?
Pollination ecology • What motivates animals to visit flowers?
• What are some ways that animals “cheat” plants? What are some ways that plants “cheat” animals?
Pollination syndromes • What do the flowers with nocturnal pollinators have in common? How do they differ?
• What is buzz pollination?
• What color and shape are flowers pollinated by hummingbirds?
• Anigozanthus (kangaroo’s paw), Strelitzia, and Protea provide support for their pollinators to perch on, but Zingiber (ginger) doesn’t. Why?
• How does a carrion fly-pollinated plant (Arum) attract pollinators?
• Vallesneria is water-pollinated. What traits does it share with wind-pollinated plants? Page 45
5/2/16
Revision: breeding systems & family ID • The African water lily separates its sexual functions over time. Which sex comes first? What is the term for this?
• How does the Arum maximize its chances of cross-pollination?
• The arctic Dryas is a member of Rosaceae. What floral traits can you observe that are characteristic of the family?
• Near the end of the film, the narrator talks about floral sex while images of dandelions are shown. What is the irony here?
Page 46