Week 17 – Monday Lecture: Sapindaceae s.l. (incl. Aceraceae and Hippocastanaceae) The Aceraceae now is included in a larger family, the Sapindaceae, which is a paraphyletic ancestral group. The Sapindaceae largely is tropical and has more variation in floral morphology. This expanded family also includes the Hippocastanaceae, the Horse Chestnut or Buckeye family. The Aceraceae and Hippocastanaceae both are monophyletic, but by recognizing those families as distinct from the traditional Sapindaceae, the Sapindaceae would be paraphyletic. So, the most workable solution is to include them all in one family, Sapindaceae. The name “Sapindaceae” is used for the larger group, because it was used as a family name before either of the others. OVERHEAD Phylogenetic nomenclature – because of the ranks (e.g., Order, Family, Genus, etc.) imposed by the Linnaean system and the rules of the International Code of Botanical Nomenclature, you can’t have a family nested within another family, or a family in a genus, etc (against the rules). However, a consensus has emerged that we want groups (no matter what rank) to be monophyletic (i.e., natural groups). Therefore, there has been a lot of lumping and splitting of traditional groups etc. Sapindaceae s.l. is a good example. However, in some of these cases the lumped groups form good clades within that are easy to recognize and have long standing names that are well-known in the botanical community, why not continue to recognize them? The International code of Phylogenetic Nomenclature is a system that is rank-free and does just that. So in that system we could have the Sapindaceae clade and the Aceraceae and the Hippocastanaceae – all clades that are easily defined and easily recognized. Therefore – I want you to recognize that these groups are now treated in the broadly circumscribed Sapindaceae, but we will recognize the narrow definition of the two clades Aceraceae and Hippocastanaceae, because of their broad use. 116 Aceraceae - the maple clade (Sapindaceae s.l.) 2 genera – Dipteronia (2 species native to central China) and Acer, which includes 110 species of trees and shrubs widely distributed throughout the Northern Hemisphere, but most prolific in central China and the eastern Himalayas with 14 species native to N. America. 1) trees or shrubs 2) leaves opposite MAD Cap Horse --> Maple, Ash, Dogwood, Caprifoliaceae, Horse chestnut. - typically palmate venation; usually simple, sometimes compound 3) Flowers: - 4-5 parted - nectary disk - formed in staminal whorls - flowers bisexual or unisexual, if the latter, then plants either mono- or dioecious, or androdioecious (some plants with perfect flowers, some plants with male flowers only; example Mountain maple – A. glabrum) - may be insect or wind pollinated - fruit of 2 fused carpels each with pronounced wing and dispersed by wind “samaroid schizocarp” Hippocastanaceae - the buckeye clade (Sapindaceae s.l.) Includes 2 genera and ca. 25 species of trees and shrubs primarily in the Americas, southeastern Europe, eastern Asia and India, with 7 species native to N. America. As a group they are not important timber producers but are very important ornamentals. Aesculus – horsechestnut The genus includes ca. 20 species of trees and large shrubs widely distributed in the northern Hemisphere. 7 species are native to N. America and are called buckeyes. European species are called horsechestnuts. 117 Acer - the maples They are important components of many forest communities and are highly valued for wood products & syrup and several species are important ornamentals. Acer – silver maple Occupies moist sites, especially bottomlands throughout much of the eastern US. Occurs in association with several other river-bottomland species, Salix, Populus, Ulmus, Acer rubrum, uncommon on dry sites. It is fairly shade tolerant. Grows rapidly, may reach 60-80' tall and 2-3' diameter at maturity. An important timber tree, the source of "soft maple" used to make pallets & crates and for pulp. A very commonly planted ornamental that has escaped cultivation in many areas. Vegetative Features: • Leaves are 4-6" long, simple, opposite, deciduous, deeply, palmately 5-lobed – light green above and silvery below. Yellow to orange in the fall. • Often distinctive vase-shape – forking/y-shaped trunk. • Shallow wide-spreading root system. • Bark is smooth and gray on young trees but develops distinctive loosely attached scales on older trees. Reproductive Features: • Polygamous (mixture of perfect and imperfect flowers) with reduced perianth, emerging very early in the spring before the leaves. • Mericarp wingss widely divergent, wings 1 1/2-2 1/2" long. • Matures early enough to take advantage of seasonally wet soils on the flood plain. • Germinate the same season. Acer rubrum – red maple Occupies variable sites from swampy bottomlands and moist alluvial soils to occasionally on rocky upland sites throughout much of eastern US. Most commonly associated with “red- maple swamps”. Formerly a minor component of many forest community types but due to fire suppression and anthropogenic disturbances it has become a major component of many forest community types. Capable of pioneering diverse sites and is moderately shade tolerant. Red flowers & fruit and fall colors in combination with ability to grow well on diverse sites have led to widespread use as an ornamental. Many cultivars exist. Wood is similar to silver maple, "soft" and used for the same purposes. May reach 50-70' tall and 1-2' diameter at maturity. 118 Vegetative Features: • Leaves are 2 1/2-4" long, simple, opposite, deciduous, palmately 3-5-lobed with serrate margins. Sinuses at right angles. Light green above, pale and glaucous below. Leaves are similar to Acer glabrum. Fall color is red! • Shallow wide-spreading root system. • Bark is smooth and gray on young trees but breaks into scaly plates on older trees. Reproductive Features: • Flowers are polygamous with reduced perianth, emerging very early in the spring before the leaves. • Mericarp wings slightly divergent approximately 3/4" long. • Fruit matures in late spring, sheds and seeds germinate in days, in time to take advantage of seasonally wet soils much like silver maple. Acer saccharum – sugar maple Occupies mesic sites of the northern and central deciduous zones, ie. east of the Mississippi except southern states. Extremely shade tolerant. Frequent associates include Betula alleghaniensis and Fagus grandifolia to form the climax community in the northern deciduous zone. Beech-maple in the central deciduous zone. Has 3-5-lobed leaves with acute to rounded apex and pubescence in the Southern portion of its range. Often designated as var. floridanum. Taxonomic disagreements. Has 3-lobed pubescent leaves with stipules in the northern portion of its range. Often designated as Acer nigrum but considerable bickering over taxonomic placement occurs. Has been in decline in the NE due possibly to acid rain and pathogens. A very important timber tree. The source of "hard" or "rock" maple used to make furniture, cabinetry and flooring. The commercial source for maple syrup and sugar. Average mature tree will produce about 16 gallons of 1-2% sugar sap which when boiled down will make about 1/2 gallon of syrup. Also very important as an ornamental. May reach 60-80' tall and 2' diameter at maturity. Vegetative Features: • Leaves are simple, opposite, deciduous, 3 1/2-5 1/2" long, palmately 5-lobed, margin entire or nearly so. Sinuses acute angles and rounded. • Apex acuminate, base cordate, bright green above and pale below with both surfaces glabrous. • Base of petiole is red in the spring. Red and yellow fall colors. • Long clear trunk under forested conditions but branches near the ground when open- grown. • Bark is gray and deeply furrowed on older trees. Reproductive Features: • Flowers are polygamous, yellow, long pubescent pedicels, emerge with the leaves. • Mericarp wings 1-1 1/4" long and parallel to slightly divergent. Mature in the fall. • Sprouts from stumps and roots. 119 Acer negundo – box-elder Most common on moist bottomlands but also found on drier & poorer soils than any other maple. Widely distributed in N. America includes most of the lower 48 (except the NW) and Alberta, Saskatchewan and Manitoba. Grows quickly and may reach 30-60' tall and 2-3 1/2" diameter at maturity. Can invade poorer and drier soils than other maples – weedy. Vegetative Features: • Leaves are pinnately (or palmately) compound, opposite and deciduous. 3-7 leaflets are short-petioled and variably toothed or lobed. The exception to the rule. • Has a ragged form with weak, easily damaged limbs. Damaged by numerous pathogens. Reproductive Features: • Dioecious, flowers are apetalous and yellow-green. Emerge with or before the leaves. Acer macropyhllum – bigleaf maple Occupies riparian and alluvial terraces in association with Populus trichocarpa, Alnus spp. and several conifers on the Pacific slope from British Columbia to Southern California. Becoming important commercially. Wood is used for veneer, paneling, furniture, pianos, woodenware and fuel. May reach 50-80' tall and 3-4' diameter at maturity. Vegetative Features: • Leaves are simple, opposite, deciduous, 6-10" long, palmately 5-lobed, bright green above paler below. • Petioles have milky sap. • Usually has a narrow crown and a long clear bole in forests but branches near the ground with wide round top when open grown. • Bark is light gray-brown and smooth on younger trees but becomes furrowed on older trees. Reproductive Features: • Polygamous, flowers are yellow-green, showy with perianth, borne in puberulent racemes. • Mericarp wings are 1-1 1/2" long and densely pubescent. 120 Acer glabrum – Rocky Mountain maple Occupies variable sites from riparian zone in drier habitats to the understory of mid-elevation conifer forests of the Cascades, Sierras and Rocky mountains. Can aggressively establish itself on disturbed sites and clearcuts with adequate moisture, (grand fir series through western red-cedar/western hemlock series). Large multi-trunked shrub or small tree may reach 30' tall and 1' diameter at maturity.