Stems - Botany

Slide 1 Stems Botany LHAP104 Slide 2 Stem morphology axillary bud (found in the axil of the leaf) may develop into a new branch with leaves or it may develop next year’s flowers note the: bud scales lenticels existing leaf petiole gobotany.newenglandwild.org Slide 3 Bud scales and leaf scars i1.wp.com/joshfecteau.com Slide 4 lfscarsplantsandrocks.blogspot.com Slide 5 Alex Shigo Slide 6 Stem anatomy When was this twig cut? a) spring b) summer c) fall d) winter How old is the twig? Alex Shigo Slide 7 Wood formation newly formed xylem vessels Alex Shigo Slide 8 Wood formation Springwood vs summerwood Alex Shigo Slide 9 Wood anatomy Vascular cambium Bark formation xylem vessels earlywood latewood parenchyma rays Alex Shigo Slide 10 Alex Shigo Slide 11 Woody dicot stems www.actforwildlife.org.uk Alex Shigo Alex Shigo Slide 12 Herbaceous dicot stems dicots that do not produce wood and shed their above-ground parts by the end of the growing season those that complete their life cycle in one year are called ANNUALS those that “return” every year are called PERENNIALS Slide 13 www.studyblue.com Slide 14 Monocot Stems Slide 15 Wikimedia Commons Slide 16 Monocot stems There is no “pith” or “cortex” in most monocot stems. There is parenchyma tissue around and in between the “bundle sheaths” as the parenchyma cells expand the vascular tissue appears to be less concentrated. The potential diameter size (girth) of a monocot stem is predetermined by the amount of parenchyma present Slide 17 Slide 18 Alex Shigo Slide 19 Growth of a monocot stem Imagine a grass plant having the same growth as this palm tree 1 3 4 2 7 5 6 Alex Shigo Slide 20 Modified Stems Bulb Corm Rhizome Stolon / runner Tuber Spines & Thorns Tendrils Slide 21 Bulbs a short stem with large fleshy storage leaves attached the leafy scales store food (energy) there is a terminal bud that will produce a leafy stem there is also at least one axillary bud that will produce a bulb for the next year examples are onions, tulips en.wikipedia.org Slide 22 vintageprintable.com Slide 23 Corms solid, erect, enlarged underground stems there are no stem leaves; just papery coverings it is the thickened stem that stores the energy there are nodes on the stem that develop into the leaves axillary buds develop into new corms examples are gladiolus, crocus en.wikipedia.org www.dummies.com Slide 24 en.wikipedia.org Slide 25 Rhizomes horizontal underground stems nodes may produce normal leaves or small scale-like leaves usually adventitious roots are formed at the nodes Slide 26 Rhizome examples: quackgrass, iris, cannas en.wikipedia.org weedypests.wikispaces.com fredgonsowskigardenhome.com Slide 27 Stolons / Runners horizontal aboveground stems they may form adventitious roots at the stem nodes when they make soil contact www.wikiwand.com Slide 28 agrowingtradition.blogspot.com Slide 29 Tubers solid, enlarged, horizontal, shortened stem, usually borne below ground. Slide 30 Spines & Thorns borne in the axils of leaves (prickles on roses are not modified stem tissue but rather just outgrowth of the epidermis) en.wikipedia.org Slide 31 Tendrils borne in the axils of leaves (compared to tendrils that a re modified leaves such as found in pea plants) commons.wikimedia.org Slide 32 Water storage stems Cactus have lost their true leaves, retaining only spines the stems are thickened and fleshy; adapted to store water