Cataphyll
Encyclopedia
In plant morphology
, a cataphyll (sometimes also called a cataphylla, or cataphyll leaf) is a leaf
whose primary function is something other than photosynthesis
. At most, cataphylls are trivially or transiently photosynthetic, and instead perform functions such as storage, protection, or structural support.
s, scaly bracts
, spines
and glochid
s. Each of these occurs in various forms and contexts; for example, bud-scales occur on various kinds of leaf or branch buds as well as on flower buds. At all events, cataphylls are sacrificial organs.
The word cataphyll derives from the Greek; in context it means something like "leaf to be broken down", implying leaves that are discarded or consumed. In fact some forms of cataphylls, such as the leaves or leaf bases forming the tunic around a corm or a bulb, are retained after they have died, and the protective presence of their remains is their major function. Similar protective masses of dead leaves encircle the stems of some species of palm trees
or aloe
s, but those are not usually regarded as cataphylls because their primary function while alive was photosynthesis, as is usual for leaves. Clearly, the precise limits of the definition of the concept is a matter of convenience in any given context.
Cotyledon
Cotyledon
s are widely regarded as a class of cataphyll, though many kinds of cotyledon function as living tissue and remain alive till the end of their function at least, at which time they wither and may drop off. They begin as leaf rudiments and many kinds accumulate nutrient materials for storage, starting to give up their stored material as the plant begins to germinate. Some, such as the cotyledon
s of many legumes, conifers
, and cucurbits
, even develop chlorophyll and perform the first photosynthesis for the germinating plant. Logically it is stretching the term to call such an organ a cataphyll, because after all, most ordinary leaves also have limited life spans and drop off when exhausted, whether after one season or several. However, non-cotyledonous leaves are not normally regarded as cataphylls just because they do not live as long as the parent plant. If non-permanent leaves were termed cataphylls, then few leaves would be anything but cataphylls; the most convincing example of non-cataphylls then might be the two persistent leaves of a Welwitschia
plant. Those two leaves of the Welwitschia must last the plant for its entire life span, typically many centuries, because the growth point, the apical meristem
, dies early in the development of the seedling. Interestingly, apart from those two main leaves, the two cotyledons of Welwitschia also are persistent in a sense; their remnants form the basis of the obconical, sideways, growth of the mouth-like slit at the top of the stem.
Such special examples aside, most cotyledons are as it were, disposable once they have performed their transient function, with or without photosynthesis, and in suitable contexts may be regarded as cataphylls. It would not be practical to demand a sharply-distinct definition for a continuous range of widely-varied functions.
Spine
It also is a matter of context and preference whether one regards any particular kind of spine
as a cataphyll or not. The terminology for glochids in particular is confusing, as they are variously and arbitrarily referred to as spines, bristles and more. Morphologically only spine
s could strictly speaking be cataphylls, because the others are not leaves, but in the current context the point is hardly worth pursuing.
Some kinds of such defensive organs remain on the plant, whereas others, such as the glochid
s of Cacti
in the sub-family Opuntioideae, not only detach when touched, but owe much of their very function to their tendency to remain stuck into the skin, respiratory system, or eyes of the victim. In either case, most of the tissue in most kinds of spines will be dead by the time the spine is ready for action, whereas at the start of its development a spine generally is soft and fleshy, alive, photosynthesising, and growing, but ineffective for defence.
. Their most spectacularly specialised examples are the often precisely imbricate
bud scales of the broad-leaved trees of boreal forest
s.
In warm temperate climates one also finds some plants with armored buds, even if there is no winter dormancy. For example, many species of sumach indigenous to temperate zones, such as (Searsia or Rhus), have naked apical buds that continue growing throughout the active season and never go into a state of dormancy before their stems lapse into senescence. However, each leaf on a shoot has an axillary bud, and not every axillary bud begins to grow as soon as it is formed; instead it might take years before there is occasion for such an axillary bud to open; it might never open at all. For protection during its dormancy, if any, the first few leaves of each axillary bud grow into a snug imbricate covering of cataphyllic bud-scales soon after the bud forms. Inspect the pictures of Searsia angustifolia for illustrations of this effect.
There are yet other classes of bud protection; large leaves of tropical plants without any dormant stage to speak of, such as Philodendron
s, often develop within an unusually large protective cataphyll, possibly functioning largely as scaffolding for the growing leaf, or protection from wind during the period when their tissue is tender and their fibres are undeveloped. The protective cataphylls curl back and dry out as the leaf opens and matures, after which they often are shed.
The protective bracts growing in and around the inflorescences of Musa
species, such as banana
s, amount to cataphylls protecting their flowers and young fruit. They die and may be shed as the inflorescence matures.
One also could argue for regarding the sepals of some plants as cataphylls. For one example, the sepals of the "cape gooseberry
" unite to form a protective cape around the fruit, becoming papery and brittle as the fruit ripens, though the cape is not specifically shed.
or Amaryllis
, are cataphylls primarily in that that part of the organ never acts as photosynthesising leaf tissue. However, that is something like special pleading, because many or most of the bulb scales were at one time just the leaf bases of photosynthesising, apparently deciduous leaves. In fact only the visible, green parts of the leaves were deciduous, and the bulb scale stayed in place as a living storage organ. On most bulbs some scales are the bases of leaves that never were photosynthetic, but immediately formed cataphylls that function either as storage organs or as protective scales, or both in turn. New leaves in true bulbs, botanically speaking, are produced from the centre, and as they grow, they force the older bulb scales outwards. The outermost scales of the plant yield up their stores to the plant each season and as their depleted tissue dies, the residue gets added to the bulb's protective tunic. Only then does the dying leaf complete its role as a cataphyll in the usual sense. Most onions live for only a few years, but undamaged Amaryllis
bulbs in the wild for example, can grow indefinitely, and each new bulb scale can take many years to reach the outside of the bulb and merge into the tunic.
Corm
Like bulb-scales, corm-scales are largely the basal parts of the photosynthetic leaves that show above ground. Some species of cormous plants, such as some Lapeirousias also produce cataphyllous leaves that act as practically nothing more than tunic leaves for the corm. Unlike bulb-scales however, the corm tunic has no significant storage function; that task is left to the parenchyma
of the cortex
of the corm.
Plant morphology
Plant morphology or phytomorphology is the study of the physical form and external structure of plants. This is usually considered distinct from plant anatomy, which is the study of the internal structure of plants, especially at the microscopic level...
, a cataphyll (sometimes also called a cataphylla, or cataphyll leaf) is a leaf
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
whose primary function is something other than photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
. At most, cataphylls are trivially or transiently photosynthetic, and instead perform functions such as storage, protection, or structural support.
Forms of cataphylls
Some kinds of cataphylls perform a transient function, after which they die and may be shed. Others cannot perform their function until they die, whether they are shed or not. Yet others perform indefinitely in the form of persistent structures that remain post-death. Examples of various kinds of cataphylls include bud-scales, bulb-scales, corm-scales, rhizome-scales, cotyledonCotyledon
A cotyledon , is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...
s, scaly bracts
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
, spines
Thorns, spines, and prickles
In botanical morphology, thorns, spines, and prickles are hard structures with sharp, or at least pointed, ends. In spite of this common feature, they differ in their growth and development on the plant; they are modified versions of different plant organs, stems, stipules, leaf veins, or hairs...
and glochid
Glochid
Glochids are hair-like spines or short prickles, generally barbed, found on the areoles of cacti in the sub-family Opuntioideae. Cactus glochids easily detach from the plant and lodge in the skin, causing irritation upon contact...
s. Each of these occurs in various forms and contexts; for example, bud-scales occur on various kinds of leaf or branch buds as well as on flower buds. At all events, cataphylls are sacrificial organs.
The word cataphyll derives from the Greek; in context it means something like "leaf to be broken down", implying leaves that are discarded or consumed. In fact some forms of cataphylls, such as the leaves or leaf bases forming the tunic around a corm or a bulb, are retained after they have died, and the protective presence of their remains is their major function. Similar protective masses of dead leaves encircle the stems of some species of palm trees
Arecaceae
Arecaceae or Palmae , are a family of flowering plants, the only family in the monocot order Arecales. There are roughly 202 currently known genera with around 2600 species, most of which are restricted to tropical, subtropical, and warm temperate climates...
or aloe
Aloe
Aloe , also Aloë, is a genus containing about 500 species of flowering succulent plants. The most common and well known of these is Aloe vera, or "true aloe"....
s, but those are not usually regarded as cataphylls because their primary function while alive was photosynthesis, as is usual for leaves. Clearly, the precise limits of the definition of the concept is a matter of convenience in any given context.
CotyledonCotyledonA cotyledon , is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...
s as cataphylls
CotyledonCotyledon
A cotyledon , is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...
s are widely regarded as a class of cataphyll, though many kinds of cotyledon function as living tissue and remain alive till the end of their function at least, at which time they wither and may drop off. They begin as leaf rudiments and many kinds accumulate nutrient materials for storage, starting to give up their stored material as the plant begins to germinate. Some, such as the cotyledon
Cotyledon
A cotyledon , is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...
s of many legumes, conifers
Pinophyta
The conifers, division Pinophyta, also known as division Coniferophyta or Coniferae, are one of 13 or 14 division level taxa within the Kingdom Plantae. Pinophytes are gymnosperms. They are cone-bearing seed plants with vascular tissue; all extant conifers are woody plants, the great majority being...
, and cucurbits
Cucurbitaceae
The plant family Cucurbitaceae consists of various squashes, melons, and gourds, including crops such as cucumber, pumpkins, luffas, and watermelons...
, even develop chlorophyll and perform the first photosynthesis for the germinating plant. Logically it is stretching the term to call such an organ a cataphyll, because after all, most ordinary leaves also have limited life spans and drop off when exhausted, whether after one season or several. However, non-cotyledonous leaves are not normally regarded as cataphylls just because they do not live as long as the parent plant. If non-permanent leaves were termed cataphylls, then few leaves would be anything but cataphylls; the most convincing example of non-cataphylls then might be the two persistent leaves of a Welwitschia
Welwitschia
Welwitschia is a monotypic genus of gymnosperm plant, composed solely of the very distinct Welwitschia mirabilis. The plant is commonly simply known as Welwitschia in English. It is known locally as !kharos or khurub , tweeblaarkanniedood , nyanka , or onyanga , among others...
plant. Those two leaves of the Welwitschia must last the plant for its entire life span, typically many centuries, because the growth point, the apical meristem
Meristem
A meristem is the tissue in most plants consisting of undifferentiated cells , found in zones of the plant where growth can take place....
, dies early in the development of the seedling. Interestingly, apart from those two main leaves, the two cotyledons of Welwitschia also are persistent in a sense; their remnants form the basis of the obconical, sideways, growth of the mouth-like slit at the top of the stem.
Such special examples aside, most cotyledons are as it were, disposable once they have performed their transient function, with or without photosynthesis, and in suitable contexts may be regarded as cataphylls. It would not be practical to demand a sharply-distinct definition for a continuous range of widely-varied functions.
SpineThorns, spines, and pricklesIn botanical morphology, thorns, spines, and prickles are hard structures with sharp, or at least pointed, ends. In spite of this common feature, they differ in their growth and development on the plant; they are modified versions of different plant organs, stems, stipules, leaf veins, or hairs...
s as cataphylls
It also is a matter of context and preference whether one regards any particular kind of spineThorns, spines, and prickles
In botanical morphology, thorns, spines, and prickles are hard structures with sharp, or at least pointed, ends. In spite of this common feature, they differ in their growth and development on the plant; they are modified versions of different plant organs, stems, stipules, leaf veins, or hairs...
as a cataphyll or not. The terminology for glochids in particular is confusing, as they are variously and arbitrarily referred to as spines, bristles and more. Morphologically only spine
Thorns, spines, and prickles
In botanical morphology, thorns, spines, and prickles are hard structures with sharp, or at least pointed, ends. In spite of this common feature, they differ in their growth and development on the plant; they are modified versions of different plant organs, stems, stipules, leaf veins, or hairs...
s could strictly speaking be cataphylls, because the others are not leaves, but in the current context the point is hardly worth pursuing.
Some kinds of such defensive organs remain on the plant, whereas others, such as the glochid
Glochid
Glochids are hair-like spines or short prickles, generally barbed, found on the areoles of cacti in the sub-family Opuntioideae. Cactus glochids easily detach from the plant and lodge in the skin, causing irritation upon contact...
s of Cacti
Cactus
A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...
in the sub-family Opuntioideae, not only detach when touched, but owe much of their very function to their tendency to remain stuck into the skin, respiratory system, or eyes of the victim. In either case, most of the tissue in most kinds of spines will be dead by the time the spine is ready for action, whereas at the start of its development a spine generally is soft and fleshy, alive, photosynthesising, and growing, but ineffective for defence.
Buds, flowers, and associated cataphylls
Bud-scales and bract-scales (or scaly bracts) are leaves that have a specific protective function with at most trivial and transient photosynthetic function; they are vital protection against pests and climate, especially during periods of dormancyDormancy
Dormancy is a period in an organism's life cycle when growth, development, and physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions...
. Their most spectacularly specialised examples are the often precisely imbricate
Aestivation (botany)
Aestivation or estivation, refers to the positional arrangement of the parts of a flower within a flower bud before it has opened. Aestivation is also sometimes referred to as praefoliation or prefoliation, but these terms may also mean vernation: the arrangement of leaves within a vegetative...
bud scales of the broad-leaved trees of boreal forest
Taiga
Taiga , also known as the boreal forest, is a biome characterized by coniferous forests.Taiga is the world's largest terrestrial biome. In North America it covers most of inland Canada and Alaska as well as parts of the extreme northern continental United States and is known as the Northwoods...
s.
In warm temperate climates one also finds some plants with armored buds, even if there is no winter dormancy. For example, many species of sumach indigenous to temperate zones, such as (Searsia or Rhus), have naked apical buds that continue growing throughout the active season and never go into a state of dormancy before their stems lapse into senescence. However, each leaf on a shoot has an axillary bud, and not every axillary bud begins to grow as soon as it is formed; instead it might take years before there is occasion for such an axillary bud to open; it might never open at all. For protection during its dormancy, if any, the first few leaves of each axillary bud grow into a snug imbricate covering of cataphyllic bud-scales soon after the bud forms. Inspect the pictures of Searsia angustifolia for illustrations of this effect.
There are yet other classes of bud protection; large leaves of tropical plants without any dormant stage to speak of, such as Philodendron
Philodendron
Philodendron is a large genus of flowering plants in the Araceae family, consisting of close to 900 or more species according to TROPICOS . Other sources quote different numbers of species. According to S.J. Mayo there are about 350-400 formally recognized species whereas according to Croat there...
s, often develop within an unusually large protective cataphyll, possibly functioning largely as scaffolding for the growing leaf, or protection from wind during the period when their tissue is tender and their fibres are undeveloped. The protective cataphylls curl back and dry out as the leaf opens and matures, after which they often are shed.
The protective bracts growing in and around the inflorescences of Musa
Musa (genus)
Musa is one of three genera in the family Musaceae; it includes bananas and plantains. There are over 50 species of Musa with a broad variety of uses....
species, such as banana
Banana
Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....
s, amount to cataphylls protecting their flowers and young fruit. They die and may be shed as the inflorescence matures.
One also could argue for regarding the sepals of some plants as cataphylls. For one example, the sepals of the "cape gooseberry
Physalis peruviana
Physalis peruviana is the plant and its fruit, also known as cape gooseberry , Inca berry, Aztec berry, golden berry, giant ground cherry, Peruvian groundcherry, Peruvian cherry , poha , ras bhari , aguaymanto , uvilla ,...
" unite to form a protective cape around the fruit, becoming papery and brittle as the fruit ripens, though the cape is not specifically shed.
Bulb-scales
Bulb scales, such as those comprising the bulb of an onionOnion
The onion , also known as the bulb onion, common onion and garden onion, is the most widely cultivated species of the genus Allium. The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion The onion...
or Amaryllis
Amaryllis
Amaryllis is a small genus of flowering bulbs, with two species. The better known of the two, Amaryllis belladonna, is a native of South Africa, particularly the rocky southwest region near the Cape...
, are cataphylls primarily in that that part of the organ never acts as photosynthesising leaf tissue. However, that is something like special pleading, because many or most of the bulb scales were at one time just the leaf bases of photosynthesising, apparently deciduous leaves. In fact only the visible, green parts of the leaves were deciduous, and the bulb scale stayed in place as a living storage organ. On most bulbs some scales are the bases of leaves that never were photosynthetic, but immediately formed cataphylls that function either as storage organs or as protective scales, or both in turn. New leaves in true bulbs, botanically speaking, are produced from the centre, and as they grow, they force the older bulb scales outwards. The outermost scales of the plant yield up their stores to the plant each season and as their depleted tissue dies, the residue gets added to the bulb's protective tunic. Only then does the dying leaf complete its role as a cataphyll in the usual sense. Most onions live for only a few years, but undamaged Amaryllis
Amaryllis
Amaryllis is a small genus of flowering bulbs, with two species. The better known of the two, Amaryllis belladonna, is a native of South Africa, particularly the rocky southwest region near the Cape...
bulbs in the wild for example, can grow indefinitely, and each new bulb scale can take many years to reach the outside of the bulb and merge into the tunic.
CormCormA corm is a short, vertical, swollen underground plant stem that serves as a storage organ used by some plants to survive winter or other adverse conditions such as summer drought and heat ....
-scales
Like bulb-scales, corm-scales are largely the basal parts of the photosynthetic leaves that show above ground. Some species of cormous plants, such as some Lapeirousias also produce cataphyllous leaves that act as practically nothing more than tunic leaves for the corm. Unlike bulb-scales however, the corm tunic has no significant storage function; that task is left to the parenchymaParenchyma
Parenchyma is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants.The term is New Latin, f. Greek παρέγχυμα - parenkhuma, "visceral flesh", f. παρεγχεῖν - parenkhein, "to pour in" f. para-, "beside" + en-, "in" + khein, "to pour"...
of the cortex
Cortex (botany)
In botany, the cortex is the outer layer of the stem or root of a plant, bounded on the outside by the epidermis and on the inside by the endodermis. It is composed mostly of undifferentiated cells, usually large thin-walled parenchyma cells of the ground tissue system. The outer cortical cells...
of the corm.