The angiosperms

1. The angiosperms sperma seed angeion case; Greek: By far the most diverse group of plants that has ever existed with more than 240,000 different species.

2. Time of origin of plant groups

3. Why are there do many species? Angiosperms Mosses Ferns Why are there so many species? Conifers

4. West Gondwana, equivalent to modern South America plus Africa Gondwanaland

5. Two things before discussing the Angiosperms: [A] Simple tissues of parenchyma, collenchyma and sclerenchyma [B] There are two classes of flowering plants, Monocotyledons and Dicotyledons

6. [A] Simple tissues of parenchyma, collenchyma and sclerenchyma epidermis collenchyma sclerenchyma xylem pholem parenchyma Transverse section Important structural tissues of many angiosperms Fig. 29.5, p. 502

7. Examples COLLENCHYMA SCLERENCHYMA PARENCHYMA Fig. 29.6, p. 502

8. Dicotyledon – Monocotyledon differences [B] There are two classes of flowering plants, Monocotyledons and Dicotyledons In seeds, two cotyledons (part of the embryo) In seeds only one cotyledon vascular bundle Vascular bundles distributed ground tissue of stem Vascular bundles arrayed as a ring in stem DICOTS Usually four or five floral parts (or multiples of these) Usually three floral parts (or multiples of three) MONOCOTS Usually a netlike array of leaf veins Usually a parallel array of leaf veins Basically, three pores of furrows in pollen grain Basically, one pore or furrow in pollen grain Fig. 29.10, p. 503

9. Principal differences between Angiosperms and Gymnosperms 1. Angiosperm leaves have finely divided venation; typically gymnosperm foliage e.g., conifer needles, have a single vascular strand 2. Angiosperm xylem contains vessels as well as tracheids and parenchyma 3. Angiosperm phloem contains sieve elements with companion cells rather than albuminous cells 4. Angiosperm ovules are protected within an enclosed structure rather sitting on a modified leaf 5. Double fertilization in the angiosperms produces a diploid zygote and triploid endosperm nucleus 6. In the angiosperms there are generally hermaphrodite flowers and cross pollinating (70%). Wind pollination is typical in the gymnosperms animal pollination widespread in angiosperms

10. 1. Leaves have finely divided venation A dicotyledon Coleus leaf cleared of cell contents and with xylem stained So? Why is that important? Typically veins are distributed such that mesophyll cells are close to a vein. The network of veins also provides a supportive framework for the leaf.

11. Leaf of a monocotyledon plant The major venation follows the long axis of the leaf and there are numerous joining cross veins so that, as with the dicotyledon, mesophyll cells are always close to a vein.

12. Diagram of a dicot leaf leaf vein (one vascular bundle inside the leaf) cuticle of upper epidermis UPPER EPIDERMIS xylem phloem PALISADE MESOPHYLL SPONGY MESOPHYLL LOWER EPIDERMIS cuticle-coated cell of lower epidermis one stoma (opening across the epidermis) Oxygen and water vapor escape from the leaf through stomata Carbon dioxide from the surrounding air enters the leaf through stomata Water and dissolved mineral ions move from roots into stems, then into leaf vein (blue arrow) My textbook has xylem and phloem wrongly labeled Products of Photosynthesis (pink arrow) enter vein and are transported to stems, roots) Fig. 29.16, p. 507

13. Tomato leaf Upper epidermis Palisade parenchyma: chloroplasts visible around cell periphery Longitudinal section through a vascular bundle Xylem vessel: annular thickening around cell wall Phloem Bundle Sheath Spongy parenchyma Lower epidermis

14. … C3 and C4 photosynthesis? Dicots Monocots

15. Leaf cross section of Zea mays ("corn"). Upper epidermis Bulliform cells Xylem Bundle sheath cells with chloroplasts Parenchyma with chloroplasts Lower epidermis Phloem http://www.uri.edu/artsci/bio/plant_anatomy/99.html

16. Anatomical separation of the C4 photosynthesis component processes Parenchyma filled with chloroplasts Bundle sheath cells filled with chloroplasts. CALVIN REACTION SITE Phloem Carbon skeleton compounds return to parenchyma C4 acids synthesized in the parenchyma move to the bundle sheath Xylem Maize 3394

17. 2. Xylem contains vessels as well as tracheids and parenchyma Wide vessel element: This kind of cell is better for fluid conduction than physical support. Tracheids provide better support but less slower rates of water conduction than vessels Vessel A vessel is composed of several vessel elements These vessel elements have completely perforated end walls Tracheid Tracheids lack perforation plates but their end walls contain numerous pits. Elongated vessel element: This cell provides moderate support but superior fluid conduction compared to a tracheid.

18. 3. Phloem contains sieve elements with companion cells Companion Cells (CC) Sieve Tube Members (STM) Sieve plate Cucurbita phloem (cucumber) STMs and CCs develop from the same progenitor cell. STMs unite vertically to form a Sieve Tube. STMs have no nucleus at maturity and depend on CC to regulate physiological processes.

19. Dicotyledon stem cross section Angelica stem transverse section Typical of a dicotyledon without secondary thickening. Four zones: J. D. Mauseth 1) epidermis 2) cortex, in many species the outermost part is a hypodermis We eat Angelica in confectionary 4) pith. 3) ring of vascular bundles Stems as diverse as slender vines, fat cacti, or as modified as potato tubers all have this organization, but with various zones modified. Cacti have an exceptionally thick cortex. Potato tubers have a gigantic pith and almost no wood.

20. Transverse section of corn stem, Zea mays. Transverse section of corn stem, Zea mays. Organization of monocotyledon stems: numerous vascular bundles distributed throughout a tissue that may be either parenchyma or collenchyma 1) epidermis 2) cortex with or without part differentiated into a hypodermis 3) vascular bundles 4) a matrix of parenchyma called conjunctive tissue or pith Monocotyledon stems: numerous vascular bundles distributed throughout a tissue that may be either parenchyma or collenchyma There are four parts: