The Araceae are usually rhizomatous or tuberous (sometimes giant) terrestrial (to rarely minute aquatic)  herbs comprising about 108 genera and 2,830 species, usually with calcium oxalate crystals or raphides and commonly with milky sap. The leaves are alternate, simple or compound, petiolate, sometimes very large, and usually with a sheathing base. The inflorescence is a fleshy spike or spadix subtended or commonly partially enveloped by a bract or spathe which is sometimes petaloid or brightly colored. The tiny flowers are actinomorphic, bisexual or unisexual, and are sessile or sometimes embedded in the floral axis. The perianth is nearly always absent in unisexual flowers but in bisexual flowers typically consists of 4-6 small, undifferentiated tepals that are free or connate. The androecium of a typical male flower usually consists of 2, 4, or 8 distinct or variously connate stamens that are opposite the tepals when these are present. The gynoecium of a typical female flower consists of a single compound pistil of mostly 3 but up to 15 carpels, a single style, and a superior ovary with sometimes one locule and 1-numerous parietal ovules or more frequently 3 or more locules, each with 1-numerous axile-apical to axile-basal ovules. The fruit is usually a berry.

Each "thumbnail" image below is linked to a larger photograph.

agl_sp_cus.jpg (8453 bytes) Aglaeonema sp., a common houseplant.
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Alocasia macrorrhiza, Araceae, 'ape. Giant herb from South and SE Asia, with huge arrowhead-shaped leaf blades up to three feet long. Closely related to taro and sometimes cultivated for the edible (after cooking) underground stem.
Amorphophallus titanum.  This aroid has a giant inflorescence.  This particular spadix attained a height of 1.37 m.
Anthurium andreanum, anthurium. Small, herbaceous plant from tropical America, grown for the long-lasting flowers (and associated bracts), which are very popular in floral arrangements. A significant commercial crop, especially of the island of Hawaii.
Caladium sp., caladium. Ornamental species grown mainly for the colorful foliage.
Colocasia esculenta, taro, kalo. Herbaceous plant from old world tropics, with thick tuber (underground stem) containing much starch; cultivated for food for many centuries. Taro was brought to Hawaii by early migrating Polynesians as the main food source. They had perhaps 300 varieties taro under cultivation at one time. The leaves of many varieties were also eaten. Taro must be cooked to destroy the acrid crystals of calcium oxalate found in all parts of the plant. Taro was so important that it had great influence on the social and individual activities of the community. One obvious ramification of taro cultivation involved water utilization. Such was the importance of taro that it was considered the plant form (kino-lau) of the great god Kane, the giver of life.
Cyrtosperma chamissonis
Dieffenbachia picta, dumb cane. The common name refers to the loss of voice that commonly occurs when any part of this plant is ingested. Note the white spadix and green spathe to the left of the spadix. The lower photo shows a single calcium oxalate crystal (raphide). Great numbers of these are released from storage "packets" into the plant sap when any part of the plant is damaged. They cause severe itching if the sap contacts the skin. If ingested, the mucous membranes are irritated. This can cause temporary loss of voice or reportedly in small children death may result.
Lysichiton americanum, skunk cabbage, Mt. Spokane, WA, 2002.
mon_del_cus.jpg (12209 bytes)
Monstera deliciosa, monstera. A spreading or climbing ornamental plant from Central America, with large, naturally perforated (fenestrated) leaves. The fruit is considered tasty by some, and has been said to combine the flavors of bananas and pineapples.
Pistia stratiotes, water lettuce. This unusual aquatic member of the family floats on the surface of ponds or streams and may have given rise to the minute aquatic species below. The swollen leaf bases have airy tissue and act as buoys to keep the plants afloat. Though tiny, especially compared to Amorphophallus titanum, the spathe and spadix nature of the inflorescence in this species is still rather typical. The upper part of the spadix has 2-8 staminate flowers and the lower part bears a single pistillate flower. A portion of a sectioned leaf with its buoyant tissue can be seen at the lower right.
Spathicarpa sagittifolia. In this unusual example of the family, the spathe and spadix are adnate and the male and female flowers are intermixed along the axis. The male flowers are the tall ones with monadelphous stamens.
Spathiphyllum x clevelandii. Note the expanded petaloid bract or spathe subtending the fleshy spike or spadix packed with minute flowers. In the top right photo is a surface view of the spadix. The perianth segments can be seen around the base of each ovary. These are bisexual flowers. The tips of a few anthers can be seen opposite the tepals. Each pistil has 3 sessile stigma lobes, suggesting the 3-carpellate nature of the gynoecium. The lower right photo is a cross-sectional view of the spadix revealing stamens at 3 and 7 o'clock and 2 of the locules in each of the ovaries at 8:30, 10:30 and 1:30. The perianth is partly visible and is pressed against the base of the ovaries in the upper left area of the photo.
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Xanthosoma sp. In the second photo the spathe has been partly cut away to reveal the flowers on the spadix. Note a few droplets of milky sap. In Araceae that have imperfect flowers, the plants are generally monoecious. Female flowers, in this case yellow, are typically located at the base of the spadix. Above these are male flowers, pink and white in this case. Sometimes the upper part of the spadix is sterile.
Lemna perpusilla, duckweed. Cosmopolitan, tiny, floating aquatic plant commonly forming a continuous green "scum" over the water surface.  These minute, aquatic derivatives of Araceae are sometimes treated as the family Lemnaceae.
Lemna, Spirodela, and Wolffia. The scale at the top of the photo is in millimeters. The medium-sized plants in the top center are Lemna. The largest plants at left and right of center are Spirodela. The tiny fusiform plants are Wolffia, representing the smallest and simplest of all flowering plants with plant bodies smaller than a pin head.

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