TheInfoList

''Luffa'' is a genus of tropical and subtropical
vine A vine (Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in relation ...

s in the cucumber family (
Cucurbitaceae The Cucurbitaceae, also called cucurbits or the gourd family, are a plant family (biology), family consisting of about 965 species in around 95 genera, of which the most important to humans are: *''Cucurbita'' – Squash (plant), squash, pumpkin, ...

). In everyday non-technical usage, the luffa, also spelled loofah, usually refers to the fruits of the species '''' and ''
Luffa acutangula ''Luffa acutangula'' is commercially grown for its unripe fruits as a vegetable. Mature fruits are used as natural cleaning sponges. Its fruit slightly resembles a cucumber or zucchini with ridges. It ranges from central and eastern Asia to southe ...
''. It is cultivated and eaten as a vegetable, but must be harvested at a young stage of development to be edible. The vegetable is popular in
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...

,
China China (), officially the People's Republic of China (PRC; ), is a country in . It is the world's , with a of more than 1.4 billion. China spans five geographical and 14 different countries, the in the world after . Covering an area of ap ...

and
Vietnam Vietnam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,, group="n" is a country in Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia or SEA, is the ...

. When the fruit is fully ripened, it is very fibrous. The fully developed fruit is the source of the loofah scrubbing sponge which is used in bathrooms and kitchens.

# Names

The name ''luffa'' was taken by European botanists in the 17th century from the Egyptian Arabic name ''lūf''.The plant name "luffa" was introduced to Western botany nomenclature by the botanist
Johann VeslingJohann Vesling (Latin: Veslingius) (1598 – 30 August 1649) was a German anatomist and botanist from Minden, Westphalia. In his youth he came to Vienna together with his father, where he later studied medicine. In 1628 he was applied as an "Inciso ...
(died 1649), who visited
Egypt Egypt ( ar, مِصر, Miṣr), officially the Arab Republic of Egypt, is a transcontinental country This is a list of countries located on more than one continent A continent is one of several large landmasses. Generally identi ...

in the late–1620s and described the plant under cultivation with artificial irrigation in Egypt. In 1706 the botanist
Joseph Pitton de Tournefort Joseph Pitton de Tournefort (5 June 1656 – 28 December 1708) was a French botanist Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic ent ...
introduced the formal botany genus name "Luffa". Tournefort referred to Veslingius's earlier description and reiterated that "Luffa Arabum" is a plant from Egypt in the cucumber family. In establishing the genus ''Luffa'', Tournefort identified just one member species and called it "Luffa Arabum". His 1706 article includes detailed drawings of this species (which is now called ''Luffa aegyptiaca''). The species is native to tropical Asia but has been under cultivation in Egypt since late medieval times. The botanist
Peter Forsskål Peter Forsskål, sometimes spelled Pehr Forsskål, Peter Forskaol, Petrus Forskål or Pehr Forsskåhl (11 January 1732 – 11 July 1763) was a Swedish-speaking population of Finland, Swedish-speaking Finnish exploration, explorer, oriental studies, ...
visited Egypt in the early–1760s and noted that it was called ''lūf'' in Arabic. In the 18th century the botanist
Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomi ...

adopted the name ''luffa'' for this species but assigned it to the genus ''
Momordica ''Momordica'' is a genus of about 60 species of annual or perennial climbers herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground, including many perennials, and nearly all annuals and biennial B ...

'', and did not use a separate genus ''Luffa''. More refs on ''Luffa'' in 18th century botanical nomenclature
"A commentary on Loureiro's "Flora Cochinchinensis" "
by E.D. Merrill, year 1935, in ''Transactions of American Philosophical Society'' volume 24 part 2, pp 377-378
''Luffa'' @ ATILF
an
"''Suite de l'Etablissement de Quelques Nouveaux Genres de Plantes''"
by J.P. de Tournefort (1706) in ''Mémoires de l'Academe Royale des Sciences année 1706''.
In
North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continen ...

it is sometimes known as "Chinese
okra Okra or Okro (, ), ''Abelmoschus esculentus'', known in many English-speaking countries as ladies' fingers or ochro, is a flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. ...

", and in Spanish as ''estropajo''.

# Uses

## Fibers

The fruit section of ''L. aegyptiaca'' may be allowed to mature and used as a bath or kitchen
sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the Diploblasts. They are Multicellular organism, multicellular organisms that have bodies full of pores and channels allowing water ...
after being processed to remove everything except the network of
xylem Xylem is one of the two types of transport tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North Ame ...

fibers. If the loofah is allowed to fully ripen and then dried on the vine, the flesh disappears leaving only the fibrous skeleton and seeds, which can be easily shaken out. Marketed as ''luffa'' or ''loofah'', the sponge is used as a body scrub in the shower. In Paraguay, panels are made out of luffa combined with other vegetable matter and recycled plastic. These can be used to create furniture and construct houses.

## Food

### Indian subcontinent

In
Hindi Hindi (Devanagari: , हिंदी, ISO 15919, ISO: ), or more precisely Modern Standard Hindi (Devanagari: , ISO 15919, ISO: ), is an Indo-Aryan language spoken chiefly in Hindi Belt, North India. Hindi has been described as a Standard la ...

-speaking
North India North India is a loosely defined region consisting of the northern part of India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest count ...

n states, it is called ''torai'' (), and cooked as vegetable. But in central/Western India, specially in Madhya Pradesh, it is called ''gilki'' (). ''Torai'' is reserved for ridge gourd and is less popular than ''gilki'' in central western India. In
Bhojpuri Bhojpuri (;Bhojpuri entry, Oxford Dictionaries
, Oxford Uni ...

speaking regions it is called ''ghiura''. Apart from fruit of the vegetable, flowers are also used as vegetable as ''chokha'', ''tarua'', ''pakoda'', etc. In
Nepal Nepal (; ne, नेपाल ), officially the Federal Democratic Republic of Nepal ( ne, सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is ma ...

and
Nepali language Nepali (; , ) is an Indo-Aryan languages, Indo-Aryan language of the sub-branch of Eastern Pahari. It is the official language at the federal level in Nepal and one of the 22 scheduled languages of India due to the Nepalese community in the Nor ...

speaking Indian states, it is called ''ghiraula'' (घिरौंला). It is popular vegetable usually cooked with tomato and potatoes and served with rice. In
Gujarat Gujarat (, ) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper i ...

it is known as ''turia'' or ''turya'' (તુરીયા) as well as or ''ghissora'' in the
Kutchi language Kutchi (; કચ્છી, , ڪچّي) is an Indo-Aryan language The Indo-Aryan or Indic languages form a major language family A language is a structured system of communication used by humans, including speech ( spoken language), g ...

. It is a simple but very popular vegetable usually made with a plentiful tomato gravy and garnished with green chillies and fresh coriander. When cooked roti is shredded by hand and mixed into it, it is colloquially known as "rotli shaak ma bhuseli". Alternatively this dish is also eaten mixed with plain cooked rice. In
Bengali Bengali or Bengalee, or Bengalese may refer to: *something of, from, or related to Bengal, a large region in South Asia * Bengalis, an ethnic and linguistic group of the region * Bengali language, the language they speak ** Bengali alphabet, the wr ...
-speaking
Bangladesh Bangladesh (, bn, বাংলাদেশ, ), officially the People's Republic of Bangladesh, is a country in South Asia South Asia is the southern region of Asia, which is defined in both geography, geographical and culture, ethno-c ...

and the Indian state of
West Bengal West Bengal (, Bengali Bengali or Bengalee, or Bengalese may refer to: *something of, from, or related to Bengal, a large region in South Asia * Bengalis, an ethnic and linguistic group of the region * Bengali language, the language they sp ...

, it is known as ''dhudhul'' () and a popular vegetable. It is eaten fried or cooked with shrimp, fish, or meat. In
Assam Assam (, ) is a state in Northeast India, northeastern India, south of the eastern Himalayas along the Brahmaputra Valley, Brahmaputra and Barak River valleys. Assam covers an area of . The state is bordered by Bhutan and Arunachal Pradesh to ...

, it is called ''bhul'' (ভুল) and is cooked with sour fish curry along with ''
taro ''Colocasia esculenta'' is a tropical plant grown primarily for its edible corm A corm, bulbo-tuber, or bulbotuber is a short, vertical, swollen underground plant stem '' has lost its leaves, but is producing adventitious rootsImportant ...

''. In
Tamil Nadu Tamil Nadu (; ) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspape ...

, the gourd is called ''peerkangai'' and used as a vegetable to make ''peerkangai
kootu Kootu (Tamil Tamil may refer to: * Tamils, an ethnic group native to India, Sri Lanka and some other parts of Asia **Sri Lankan Tamils, Tamil people native to Sri Lanka **Tamil Malaysians, Tamil people native to Malaysia * Tamil language, a D ...
'', ''
poriyal ''Poṟiyal'' ( ta, பொரியல்) is the Tamil people, Tamil word for a fried, or sometimes sauteed, vegetable dish. The Kannada word for the same dish is ''Palya'' and in Telugu language, Telugu, it is ''Vepudu'' and in Malayalam it is ...
'', and '' thogayal''. Even the skin is used to make chutney. In
Karnataka Karnataka (; ISO The International Organization for Standardization (ISO; ) is an international standard are technical standards developed by international organizations (intergovernmental organizations), such as Codex Alimentarius in f ...

's
Malenadu Malenadu (; simplified as Malnad) is a region in the state of Karnataka Karnataka (ISO 15919, ISO: , ) is a States of India, state in the south western region of India. It is the largest state in South India and sixth largest in India. It ...
(
Western Ghats The Western Ghats is a mountain range that covers an area of in a stretch of parallel to the western coast of the Indian peninsula, traversing the states State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', ...

) it is known as ''tuppadahirekayi'', which literally translates as "buttersquash", also known as Hirekayi in
Kannada Kannada (; ಕನ್ನಡ, ; less commonly known as Kanarese) is a Dravidian language Dravidian languages (or sometimes Dravidic languages) are a family of languages In human society, family (from la, familia) is a group of peop ...

. It grows naturally in this region and is consumed when it is still tender and green. It is used as a vegetable in curries, but also as a snack, ''bhajji'', dipped in chickpea batter and deep fried. In
Tulu language Tulu () in Kannada script The Kannada script (IAST: ''Kannaḍa lipi''; obsolete: Kannara, Kanarese or Canarese script) is an abugida of the Brahmic scripts, Brahmic family, used primarily to write the Kannada language, one of the Dravidi ...
it is known as Peere and is used to prepare chutney and ajethna. In
Telangana Telangana (, , ) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspape ...

, it is called ''beerakaya''. It is used in making Dal, Fry, Roti Pacchadi and wet curry. In
Andhra Pradesh Andhra Pradesh (English: Telugu: ) is a States and union territories of India, state in the south-eastern Coastal India, coastal region of India. It is the List of states and union territories of India by area, seventh-largest state by area c ...

, it is called ''nethi beerakaya'' or ''beerakaya''. And in
Assam Assam (, ) is a state in Northeast India, northeastern India, south of the eastern Himalayas along the Brahmaputra Valley, Brahmaputra and Barak River valleys. Assam covers an area of . The state is bordered by Bhutan and Arunachal Pradesh to ...

it is called ''jika'' (জিকা,
Luffa acutangula ''Luffa acutangula'' is commercially grown for its unripe fruits as a vegetable. Mature fruits are used as natural cleaning sponges. Its fruit slightly resembles a cucumber or zucchini with ridges. It ranges from central and eastern Asia to southe ...
) and ''bhula'' (ভোল, ). It is used as a vegetable in a curry, chutney and stir fry. In
Kerala Kerala ( ; ) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper ...

, it is called ''peechinga''; in the Palakkad area it is particularly called ''poththanga'' and used in while bathing. It is also used as a vegetable, cooked with dal or stir fried. Fully matured fruit is used as a natural scrub in rural Kerala. In some places such as
Wayanad Wayanad (), is an Districts of India, Indian district in the north-east of Kerala state with administrative headquarters at the municipality of Kalpetta. It is the sole Plateau in Kerala. The Wayanad Plateau forms a continuation of Mysore Platea ...

, it grows as a creeper on fences. In
Maharashtra Maharashtra (; , abbr. MH or Maha, is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper) ...

, India, (ridge gourd luffa) and ''ghosavala'' (smooth luffa) are common vegetables prepared with either crushed dried peanuts or with beans. In
Manipur Manipur () is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper in ...

,
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...

, is cooked with other ingredients like potato, dried fish, fermented fish and served. It is also steamed and consumed or crushed () with other ingredients and served with steamed rice (''chaak''). Fried ones () are also favorites for many. ''Sebot'' is also eaten as a green vegetable

### Other Asian cuisines

In
Vietnamese cuisine Vietnamese cuisine encompasses the foods and beverages of Vietnam, and features a combination of five fundamental tastes ( vi, ngũ vị) in overall meals. Each Vietnamese dish has a distinctive flavor which reflects one or more of these ele ...
, the
gourd Gourds include the fruits of some flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Gre ...

is called "'" and is a common ingredient in soups and stir-fried dishes. In China and Taiwan (where it is called , or in English, "silk melon"), Indonesia (where it is called ''oyong''), and the
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

(where it is called ''patola'' in
Tagalog Tagalog may refer to: Language * Tagalog language Tagalog (, ; ) is an Austronesian languages, Austronesian language spoken as a first language by the ethnic Tagalog people, who make up a quarter of the population of the Philippines, and as a se ...
and ''kabatiti'' in Ilokano), in
Timor-Leste East Timor () or Timor-Leste (; tet, Timór Lorosa'e), officially the Democratic Republic of Timor-Leste ( pt, República Democrática de Timor-Leste, tet, Repúblika Demokrátika Timór-Leste), is an island country An island country or ...
it is also called "patola" or "batola" in
Tetum Tetum ( pt, Tetum ,; tet, Tetun ) is an Austronesian language The Austronesian languages (, , , ) are a language family A language is a structured system of communication used by humans, including speech ( spoken language), gestures (Si ...
and in Manipur, India, (where it is called ) the luffa is eaten as a green vegetable in various dishes. In
Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an in ...

it is called ''hechima'' () and is cultivated all over the country during summer. It is commonly used as a green vegetable in traditional dishes of the
Ryukyu Islands The , also known as the or the , are a chain of Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or ...

(where it is called ''naabeeraa''). In other regions it is also grown for uses other than food.

### Western cuisines

Luffa is also known as "Chinese
okra Okra or Okro (, ), ''Abelmoschus esculentus'', known in many English-speaking countries as ladies' fingers or ochro, is a flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. ...

" in
Canada Canada is a country in the northern part of North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, ...

and the
U.S. The United States of America (USA), commonly known as the United States (U.S. or US), or America, is a country primarily located in North America North America is a continent entirely within the Northern Hemisphere and almost all ...
.

## Other uses

In Japan, in regions other than the Ryukyu Islands and Kyushu, it is predominantly grown for use as a sponge or for applying soap, shampoo, and lotion. As with
bitter melon ''Momordica charantia'' (colloquially: bitter melon; bitter apple; bitter gourd; bitter squash; balsam-pear; with many more #Alternative names, names listed below) is a tropical and subtropical vine of the family Cucurbitaceae, widely grown in A ...

, many people grow it outside building windows as a natural sunscreen in summer.

# Role in food chain

Luffa species are used as food plants by the
larva A larva (plural larvae ) is a distinct juvenile form many animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that f ...
e of some
Lepidoptera Lepidoptera ( ; ) is an order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or ...

species, including ''
Hypercompe albicornis ''Hypercompe albicornis'' is a moth of the family Erebidae Species description, first described by Augustus Radcliffe Grote in 1865. It is found on Cuba. Larvae have been recorded feeding on ''Helianthus'', ''Luffa'' and ''Phaseolus'' species. R ...
''.

# Mechanical Properties

The luffa sponge is as
biological Biology is the natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes knowl ...

cellular material. These materials often exhibit exceptional
mechanical properties Mechanical may refer to: Machine * Mechanical system A machine is a man-made device that uses Power (physics), power to apply Force, forces and control Motion, movement to perform an action. Machines can be driven by Animal power, animals and ...
at low
densities The density (more precisely, the volumetric mass density; also known as specific mass), of a substance is its mass per unit volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter Rho (letter), rho), although the L ...

. While their mechanical performance tends to fall behind manmade materials such as
alloys An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts Elec ...
,
ceramics A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant Corrosion is a Erosion, natural process that converts a refined metal into a more chemically stable form such as oxide, hydroxide, carbonate or sulfide. It ...

,
plastics Plastics are a wide range of syntheticA synthetic is an artificial material produced by organic chemistry, organic chemical synthesis. Synthetic may also refer to: In the sense of both "combination" and "artificial" * Synthetic chemical or s ...

, and , as a
structural material Structural engineering depends on the knowledge of materials and their properties, in order to understand how different materials resist and support loads. Common structural materials are: Iron Wrought iron Wrought iron is the simplest form o ...
, they have long term
sustainability Sustainability is the capacity to endure in a relatively ongoing way across various domains of life. In the 21st century, it refers generally to the capacity for Earth's biosphere and human civilization to co-exist. For many, sustainability is ...

for the natural environment. When compressed longitudinally, a luffa sponge is able to absorb comparable energy per unit mass as aluminum foam. Luffa sponges are composed of a complex network of
fiber Fiber or fibre (from la, fibra, links=no) is a natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including ...

bundles connected to form a 3-dimensional, highly-
porous Porosity or void fraction is a measure of the (i.e. "empty") spaces in a , and is a of voids over the total volume, between 0 and 1, or as a between 0% and 100%. Strictly speaking, some tests measure the "accessible void", the total amount of vo ...
network. The hierarchical structure of luffa sponges results in mechanical properties that vary with the component of sponge tested. Specifically, the mechanical properties of fiber bundles differ from those of blocks from the bulk of the sponge, which differ from those of the cross sections of the entire sponge.

## Fiber Bundles

Uniaxial tensile tests of fiber bundles isolated from the inner surface provide insight this basic
strut A strut is a structural component commonly found in engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The d ...

element of the luffa sponges. These fibers bundles vary in
diameter In geometry Geometry (from the grc, γεωμετρία; ' "earth", ' "measurement") is, with , one of the oldest branches of . It is concerned with properties of space that are related with distance, shape, size, and relative position ...

from 0.3 to 0.5 mm. Each fiber bundle has a low density core region not occupied by fibers. The stress-strain response of the fiber bundles is nearly linear elastic all the way until
fracture Fracture is the separation of an object or material into two or more pieces under the action of stress (physics), stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the ...

, suggesting the absence of
work hardening #REDIRECT Work hardening#REDIRECT Work hardening Work hardening, also known as strain hardening, is the strengthening of a metal or polymer by plastic deformation. Work hardening may be desirable, undesirable, or inconsequential, depending on th ...
. The
slope In mathematics, the slope or gradient of a line Line, lines, The Line, or LINE may refer to: Arts, entertainment, and media Films * ''Lines'' (film), a 2016 Greek film * ''The Line'' (2017 film) * ''The Line'' (2009 film) * ''The Line'', ...

of the
linear Linearity is the property of a mathematical relationship (''function Function or functionality may refer to: Computing * Function key A function key is a key on a computer A computer is a machine that can be programmed to carry out se ...

region of the stress-strain curve, or
Young’s modulus Young's modulus E, the Young modulus, or the modulus of elasticity An elastic modulus (also known as modulus of elasticity) is a quantity that measures an object or substance's resistance to being deformed elastically (i.e., non-permanently) wh ...
, is 236* MPa. The highest stress achieved before fracture, or
ultimate tensile strength Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle tensi ...
, is 103 MPa. The strain at which failure occurs, or failure strain, is small at only 5%. The mechanical properties of fiber bundles decrease dramatically when the size of the hollow region inside the bundle increases.  Despite their low tensile strength, the fiber bundles have a high specific modulus of 2.07– 4.05 MPa⋅m3/kg, and their overall properties are improved when a high ratio of their cross sectional area is occupied by fibers, the fibers are evenly distributed, and there is strong adhesion between fibers.

## Bulk Sponge

Block samples (height: 12.69 ± 2.35 mm, width: 11.30 ± 2.88 mm, length: 13.10 ± 2.64mm) cut from the core region and hoop region of the luffa sponge exhibit different mechanical behaviors under compression depending on both the orientation they are loaded in as well as the location in the sponge they are sampled from. The hoop region consists of the section of sponge located around the outside between the inner and outer surfaces, while the core region is from the sponge center. Samples from both the hoop and core regions exhibited yielding when compressed in the longitudinal direction due to the
buckling In structural engineering Structural engineering is a sub-discipline of in which s are trained to design the 'bones and muscles' that create the form and shape of man-made structures. also must understand and calculate the , strength, and ...

of fibers. With the highly aligned fibers from the inner surface removed from the hoop region block samples, this yield behavior disappears. In general, the inner surface fibers most significant impact the longitudinal properties of the luffa sponge column followed by the circumferential properties. There is no noticeable contribution to the
radial Radial is a geometric term of location which may refer to: Mathematics and Direction * Vector (geometric), a line * Radius, adjective form of * Radial distance, a directional coordinate in a polar coordinate system * Radial set * A bearing from ...

properties. Additionally, the core region exhibits lower
yield stress In materials science The interdisciplinary Interdisciplinarity or interdisciplinary studies involves the combination of two or more academic discipline An academic discipline or academic field is a subdivision of knowledge that is ...
and energy absorption (as determined by the area under the stress-strain curve) compared to the hoop region due to its greater
porosity Porosity or void fraction is a measure of the void Void may refer to: Science, engineering, and technology * Void (astronomy) Cosmic voids are vast spaces between filaments (the largest-scale structures in the universe The universe ( ...
. Overall, the stress-strain curves of block samples exhibit three stages of mechanical behavior common to porous materials. Namely, the samples follow
linear elasticity Linear elasticity is a mathematical model of how solid objects deform and become internally stressed due to prescribed loading conditions. It is a simplification of the more general nonlinear theory of elasticity and a branch of continuum mechan ...
for strains less than 10%, followed by a plateau for strains from 10% to 60%, and finally a stress increase associated with densification at strains greater than 60%. Segment samples created from cross sections of the entire luffa sponge (diameter: 92.51 ± 6.15 mm, height: 19.76 ± 4.95 mm) when tested in compression exhibit this same characteristic behavior. The three stages can be described by the equations: # Linear elasticity region: $\sigma=E^*\varepsilon$ for $\varepsilon\le\varepsilon_e$ # Plateau region: $\sigma=\sigma_p^*$ for $\varepsilon_e<\varepsilon\le\varepsilon_D\left(1-1/D\right)$ # Densification region: $\sigma=\sigma_p^*/D^m$ for $\varepsilon>\varepsilon_D\left(1-1/D\right)$ In the above equations, $E^*$ and $\sigma_p^*$ are the
Young's modulus Young's modulus E, the Young modulus, or the modulus of elasticity An elastic modulus (also known as modulus of elasticity) is a quantity that measures an object or substance's resistance to being deformed elastically (i.e., non-permanently) wh ...
and the
yield strength In materials science The Interdisciplinarity, interdisciplinary field of materials science, also commonly termed materials science and engineering, covers the design and discovery of new materials, particularly solids. The intellectual origi ...
of the sponge material. These are chosen to best fit
experimental data Experimental data in science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes knowledge in the form of Testability, testable explanatio ...
. The strain at the
elastic limit In materials science The interdisciplinary Interdisciplinarity or interdisciplinary studies involves the combination of two or more academic discipline An academic discipline or academic field is a subdivision of knowledge that is ...
, where the plateau region begins, is denoted as $\varepsilon_e$, while the strain at the onset of the densification region is $\varepsilon_D$. $\varepsilon_D=1-1.4\left(\rho^*/\rho_s\right)$ Here $\rho^*$ is the density of the bulk sponge $\rho_s$ is the density of its constituent, the fiber bundle. The constant D defines the strain at the onset of densification as well as the stress relationship in the densification region. It is determined by fitting experimental data.

The mechanical properties of Luffa sponges change under different strain rates. Specifically, energy adsorption,
compressive stress In long, slender structural elements — such as columns or truss Typical detail of a steel truss, which is considered as a revolute joint A truss is an assembly of beams or other elements that creates a rigid structure. In engineering, a tr ...
, and plateau stress (which is in the case of foam materials corresponds to the
yield stress In materials science The interdisciplinary Interdisciplinarity or interdisciplinary studies involves the combination of two or more academic discipline An academic discipline or academic field is a subdivision of knowledge that is ...
) are enhanced by increasing the strain rate. One explanation for this is that the luffa fibers undergo more axial deformation when dynamically loaded (high strain rates) then when quasi-statically loaded (low strain rates).

# Gallery

File:Leiden University Library - Seikei Zusetsu vol. 26, page 023 - 苦瓜 - Momordica charantia L. - 糸瓜 - Luffa cylindrica (L.), 1804.jpg , Luffa, illustration from the Japanese agricultural encyclopedia Seikei Zusetsu (1804) File:Luffa cylindrica1.jpg , Habitus of the vine File:Luffa plant.jpg , Luffa in a coconut tree File:Glands in probract that attract ants.jpg, Extrafloral nectar glands in
Luffa acutangula ''Luffa acutangula'' is commercially grown for its unripe fruits as a vegetable. Mature fruits are used as natural cleaning sponges. Its fruit slightly resembles a cucumber or zucchini with ridges. It ranges from central and eastern Asia to southe ...
and
Oecophylla smaragdina ''Oecophylla smaragdina'' (common name Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common Boston Common (also known as the Common) is a central public park in downtown Boston, Massachusetts. I ...

ants File:பீர்க்கு இலை, சென்னை,ஜூன் 2020.jpg, Luffa leaf File:Natural loofah luffa sponges on an organic farm in Israel.jpg , A bag of dried mature luffa fruits. File:Luffa aegyptiaca MHNT.BOT.2011.3.94.jpg , ''Luffa aegyptiaca'', fruit and seeds - MHNT File:Luffa operculata MHNT.BOT.2011.3.93.jpg , ''Luffa operculata'', fruit - MHNT File:Luffa sponge.png , A luffa sponge whose coarse texture helps with
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have differ ...

polishing File:Spongegourd.jpg , '''' sponge section magnified 100 times File:Luffa acutangula seeds.jpg , ''Luffa acutangula'' seeds. Each division of the ruler is 1 mm. Seeds of ''Luffa aegyptica'' look very similar. File:Pollens of Luffa.jpg, Pollen grains of Luffa File:Lufa flowers.jpg, Luffa flowers