Cornaceae Bercht. & J.Presl

Every, J.L.R. (2010). Neotropical Cornaceae.

Morphology

Description

Trees or shrubs. Leaves opposite or alternate , simple , margins entire or denticulate , primary venation pinnate , arching, trichomes T-shaped, branched or simple when present; stipules very rarely present. Inflorescences terminal occasionally axillary , cymose, involucres petal -like. Flowers bisexual (rarely unisexual and dioecious ), small, actinomorphic ; sepals 4(-10), connate , adnate to ovary ; petals 4(-10), free , valvate ; stamens alternipetalous and equal in number to petals, free , anthers dorsifixed, dehiscing via full-length longitudinal slits; ovary inferior, carpels 2, syncarpous. Fruit a grooved, globose or ovoid drupe . Seeds 2, flat.

General Description

Notes on delimitation

• Cornus L. is placed in the Cornaceae which typifies the Cornales currently placed in the Asterid clade. (APG III, 2009).

Number of genera

• Cornus L.: Cornus disciflora DC., C. excelsa Kunth, C. florida L. and C. peruviana J. F. Macbr.  growing in the Neotropics.
• Nyssa L.: with two species (N. sylvatica Marshall and N. talamancana Hammel & N.Zamora) in Mexico to Panama.

Status

• Native. 

Distribution

Distribution in the Neotropics

• Found predominately at high elevations (1,400-3,000m above sea level) below the forest canopy in mountainous regions of Central America, Bolivia, Colombia, Ecuador, Mexico and Peru.
• Also cultivated in Brazil as an ornamental and for its wood throughout most of the Neotropical countries.

Diagnostic

Distinguishing characters (always present)

• Actinodromousvenation.
• Involucres of petal -like bracts subtend the inflorescences.
• Sepals adnate to ovary.
• Petals valvate.
• Ovary inferior.
• Epigynous disk on top of ovary.
• Drupaceousfruit.

Other important characters

• A handy diagnostic trick in the field is to remove a suspected leaf, fold the leaf blade in half horizontally to form a crease, do this repeatedly until you are able to gently tear the leaf along the crease and gently pull it apart. The bottom half of the leaf will appear to hang in mid air, but on closer inspection you can see sticky threads stemming from the leaf veins.

Key differences from similar families

• Some Viburnum species look similar to Cornaceae, but the latter often have 4-merous flowers, they lack stellateindumentum, and their lateralveins ascend towards the apex of the blade (Stevens, 2008 onwards).

Notable genera and distinguishing features

• See distribution.

Literature

Important literature

APG III. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants. Botanical Journal of the Linnean Society. Vol 161: 3. Pp. 105-121.

Kubitzki, K. 2004. Cornaceae.  In: Kubitzki, K. (ed.), The Families and Genera of Vascular Plants, vol. VI, pp. 82-90. Springer Verlag, Berlin.

Lentz, D. L. 2004. Cornaceae. In: Smith, N., Mori, S. A., Henderson, A., Stevenson, D. W. and Heald, S. V. (eds). Flowering Plants of the Neotropics. Pp. 117-8. The New York Botanical Garden, Princeton University Press, Princeton.

Smith, N. 2004. Nyssaceae: In: Smith, N., Mori, S. A., Henderson, A., Stevenson, D. W. and Heald, S. V. (eds). Flowering Plants of the Neotropics. Pp. 273-274. The New York Botanical Garden, Princeton University Press, Princeton.

Stevens, P. F. 2008. Angiosperm Phylogeny Website. Version 9 onwards. http://www.mobot.org/MOBOT/research/APweb/.

Watson, L. and Dallwitz, M.J. (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version 3rd March 2009. www.delta-intkey.com.

Cornaceae, J. F. M. Cannon. Flora Zambesiaca 4. 1978

Habit

Trees, shrubs, rarely perennial herbs or woody lianes

Leaves

Leaves opposite or less commonly alternate, simple, exstipulate

Flowers

Flowers hermaphrodite or unisexual (then the plants usually monoecious or polygamodioecious), actinomorphic in cymes or panicles, umbels or rarely in capitula and then with large petal-like bracts

Calyx

Calyx-tube adnate to the ovary, sepals 4–5

Corolla

Petals 4–5 (rarely lacking), aestivation imbricate or valvate

Androecium

Stamens the same number as the petals and alternating with them, anthers 2-celled dehiscing laterally or rarely introrsely

Gynoecium

Ovary inferior, with (1)2–4 locules Style 1 or several rising from a glandular disk Placentation usually axile, with 1 anatropous pendulous ovule in each loculus Ovules with 1 integument

Fruits

Fruit typically a drupe, sometimes a berry

Seeds

Seed with copious endosperm and a small embryo

Alangiaceae, J. F. M. Cannon. Flora Zambesiaca 4. 1978

Habit

Trees or shrubs, sometimes spiny (but not in FZ area)

Leaves

Leaves alternate, entire to very slightly undulate or lobed; distinctly petiolate, often somewhat asymmetric at the base, stipules 0

Flowers

Flowers hermaphrodite regular, in few-flowered (in FZ area) axillary cymes with articulated pedicels

Calyx

Calyx truncate or with 4–10 teeth

Corolla

Petals 4–10, valvate, linear, becoming strongly recurved at maturity, sometimes slightly coherent at the base

Androecium

Stamens the same number as and alternating with the petals, or up to 2–4 times as many; free or connate at the base, more or less villous adaxially; anthers 2-locular, linear

Nectaries

Disk subglobose, flattened above

Gynoecium

Ovary inferior, 1–2-locular, style simple, clavate or 1–3-lobed; ovules solitary, pendulous in the loculi, with 2 integuments

Fruits

Fruit drupaceous, crowned with the remains of the disk and sepals, l(2)-seeded

Seeds

Seeds with the embryo about equalling the endosperm

Alangiaceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:2. 1958

Habit

Trees or shrubs, sometimes spiny

Leaves

Leaves alternate, simple; stipules absent

Flowers

Flowers hermaphrodite, actinomorphic, in axillary cymes; pedicels articulated

Calyx

Calyx truncate or with 4–10 teeth

Corolla

Petals 4–10, mostly linear, valvate, at length recurved, sometimes coherent at the base

Androecium

Stamens the same number as and alternate with the petals or 2–4 times as many, free or slightly connate at the base, more or less villous inside; anthers 2-celled, linear, opening lengthwise

Nectaries

Disk cushion-like

Gynoecium

Ovary inferior, 1–2-celled; style simple, clavate or lobed; ovule solitary, pendulous

Fruits

Fruit a drupe crowned by the sepals and disk, 1-seeded

Seeds

Seeds with the embryo about equal to the endosperm

Alangiaceae, B. Verdcourt. Flora of Tropical East Africa. 1958

Habit

Trees or shrubs, often spiny

Leaves

Leaves alternate, exstipulate, petiolate, entire or lobed, often asymmetric at the base

Flowers

Flowers hermaphrodite, regular, in few to many-flowered axillary cymes

Calyx

Calyx truncate or divided into 4–10 lobes, or denticulate

Corolla

Petals 4–10, linear, valvate, often joined at the extreme base

Androecium

Stamens equal in number to the petals and alternating with them or up to four times as many, free or slightly joined at the base

Gynoecium

Style simple, clavate or 2–3-lobed Ovary inferior, 1–2-celled, ovules solitary and pendulous in the cells

Fruits

Fruit a drupe crowned with sepals and disc, 1–2-seeded; seeds albuminous