THERMOnastic TROPISM

Eleni Katrini | Ruchie Kothari | Mugdha Mokashi Bio_Logic Lab School of Architecture, Carnegie Mellon University

abstract

Motivation: To develop dynamic elements which respond to changes in temperature

Approach: The thermonastic movements of the Tulip flower were looked at for inspiration to develop conceptual systems based on movement and heat. The tulip flower opens and closes its petals based on the external temperature. The petals open up when the temperature is high and close when the temperature is low. This movement of the petals is facilitated by movement of water through the plant. Experiments were conducted using paper which is a fibrous material exhibiting properties similar to that of a flower petal. Water at different temperatures was studied as a conducting medium.

Findings: Based on analysis, different forms of flowers were created. This includes flowers with varying surface areas, flowers made using composite materials, laminated and chiseled flowers, flowers with varying edge exposure etc. The study was focused on exploring the effects of capillary action on fibrous materials. The observations were focused on- - Range of movement of petals - Duration for capillary action - Effect of hot and cold temperature It was seen that the range of movement was the same for most of the prototypes. All the flowers other than the flowers for which the range of movement was restricted opened up to 180o. The time taken for the water to rise depended on the density and the surface area of the paper in contact with the water. Increase in density of the paper in contact with water, increases the time taken for the water to rise up. Increase in the surface area of the paper in contact with water, decreases the time taken for the water to rise up. The water rises up faster when the water is hot as compared to when the water is cold.

Implications: Even though we were able to understand techniques to create units which opened up due to temperature changes, we were not able to find a technique to reverse the movement. It is necessary to study the effect of temperature on sturdier materials

which can be used for practical applications. tulip x-ray The Tulip Kingdom: Plantae | Order: Liliales | Family: Liliaceae | Genus: Tulipa The tulip belongs to the genus tulipa which comprises of 109 species. It is a perennial bulbous plant that blooms over the spring. The tulip is indigenous to mountainous areas with temperate climates. like Southern Europe, North Africa, Anatolia, Iran and the Northwest of China.

Plant Description: The height of the tulip plant varies depending on the species of the plant. Its height ranges from 4” (10cm) to 28” (71cm). In most species, each stem produces only one flower. The stem has few leaves (2-6), that are strap shaped, with a waxy coating. They TULIP are arranged alternatively on the stem.The flowers are either cup shaped or star- The tulip is a perennial, bulbous plant with showy flowers in the genus Tulipa, which shaped and they have 3 petals and 3 sepals. The petals as well as sepals are usually comprises 109 species and belongs to the family Liliaceae. referred to as tepals as they are the same color. The tepals have darker coloring at the base. The tulip comes in a wide variety of colors. Its petals are edible.

Environmental Conditions and Adaptive Strategies: The tulip is found in temperate climates which are characterized by cold winters and dry hot summers. It has several adaptive features which help it survive in this climate. During the winter the plant is dormant. Low winter temperatures of 5-10oC are essential to accelerate the process of vernalisation. The bulb grows to a vegetative state during this period and the plant acquires the ability to flower. This ensures that the plant flowers during spring and not autumn. Seed production takes place during the spring when the bulb grows to a reproductive stage.

Physical adaptations The bulb has a fleshy inner part which is protected by a dry outer membrane. It grows deep underground for protection from the extreme summer and winter temperatures and stores food for the dormant period. The leaves are waxy to protect from MEDICAGO MARINA premature drying during the summer. The flower closes during the winter to protect its reproductive organs and opens during the summer at an average temperature of 20oC. It intuitively knows that the temperature is too low for pollination. Once the temperature rises, the flower opens up to aid pollination. The flower itself is vibrant and has a delicate scent to attract its pollinators –beetles, syrphid flies, nectar wasps CROCUS and bees. The insects are also attracted to tulip flower due to its bowl shape which stores the heat from the sun and offers a warm shelter to the insects. The open cup Crocus (plural: crocuses, croci) is a genus in the iris family comprising about 80 species shape enables an easy landing for the insects. of perennials growing from corms. Crocus’ opening and closing blossoms during day and The opening and closing movement of the flower is due to change in temperature as night is an example of thermonastic movement. opposed to sunlight which is common for most flowers. This is the reason the tulip Medicago marina is a plant species of the genus Medicago. It is native to the Mediterra- was selected for analysis for this study. nean basin but is found worldwide. A. leaves during the day B. leaves asleep at night Background

Nature exhibits a great diversity of species. The differences in the habitat of a species result in the different forms of morphological adaptations within the species. Plants, like other organisms, have their own unique way of responding to their natural environment. The growth and turgor movement exhibited within the plants is termed as “tropism”, and the generalised plant responses to external stimulus are called as “nastic movements”. The opening of bud scales and of flower petals, growth movements that occur in response to stimuli, such as light and heat, are examples of such nastic movements. Tropism in plants is triggered due to the presence of certain Changes in Gentiana algida corolla width vs. temperature over a representative day in hormones known as “auxins” which are responsible for the cell growth. the alpine. Corolla width is denoted by open diamonds, internal corolla temperature Many plant movements are controlled by both endogenous and exogenous signals. (air temperature near the base of the ovary) is denoted by solid circles, and ambient air Response to temperature is an example which is an effect of endogenous signal within temperature within 2 cm of measured corollas are denoted by x’s. Measurements were the plant due to an exogenous stimuli, which is heat. Some spring flowers like the taken at the alpine fellfield site in the Medicine Bow Mountains of southeastern Wyoming Crocus or Tulips respond to warmth and are termed as thermonastic plants. on 13 August.

Dov Koller, in his book “The Restless Plant” explains how Tulips and Crocus flowers open in response to a small increase in ambient temperature and close in response to lowering temperature. The adaxial tissues on the upper side of the perianth of the flowers exhibits an abrupt increase in length in response to a 10o C rise in temperature. The abaxial tissue on the lower side of the perianth exhibits a similar increase in response to a 10o C decrease in temperature. This phenomenon is supported by Woods (1953) in his works wherein he states that the thermonastic movement in flowers depends on the growth difference of the two sides of the perianth segments. The optimum temperature for the growth of upper side being higher than that of the lower side causes the petals to bend outwards during high temperatures and inwards during low temperatures. Work of Pfeffer(1897) on the flowers of Crocus and Tulipa demonstrate that the crocus are more sensitive to temperature than tulipa. His work states that flowers of some Crocus plant opened to an extent with fluctuations of only 0.5o C. This research was further developed upon by F.M Andrews who experiments in order to prove that the flowers of one species of Crocus, Crocus Vernus, are capable of responding to temperature change smaller than 0.5o C. His experiments showed that the flowers of Crocus Vernus opened with just an increase of 0.2o C, while the tulips exhibited a tendency to open with a change of less than 1o C. Corolla width expressed as percentage of maximum opening vs. corolla temperature for The paper “Phosphorylation of Plasma Membrane Aquaporin Regulates Temperature- three different rainfall events that occurred between 1210 and 1740 at the alpine fellfield Dependant site on three different days (19 July, 4 August, and 6 August). Each symbol represents a different plant (N 5 3) and rain event. transpiration opening in Tulip Petals”(2004) further researches on the relation between temperature- dependant petal opening and water transport from other parts to the petals. The study focuses on the effects of phosphorylation, which is a plant mechanism, of aquaporin (water channeling protein) that facilitates the transport of water at temperatures higher than 20o C, which in turn results in the opening of petals.

Various other articles from the Oxford Journals provide another perspective to the same study. The other researches conducted, show that the thermonastic properties of the flowers also assist the delicate organ in protecting itself against harsh natural conditions such as thunderstorms, rain or snow. The blossom closure helps to protect turgor the reproductive organs inside the corolla and the flower opens during warmer PRESSURE temperature attracting bees and flies which in turn assist with the pollination. Thus, the research and paper so far indicate the involvement of internal mechanism influenced by external stimuli of “heat” which results in the opening and closing of certain flowers, such as the Tulipa or Crocus. This thermonastic movement is also termed as oscillation of petals.

CAPILLARY System action

The opening and closing of the flower is enabled by water transport and transpiration in the plant.

The petals of the flower open up when water from other parts of the plant reach the base of the petals. The volume of the petal cells increases due to turgidity and causes the petals to open up. The petals close when the amount of water reaching the OSMOSIS petal cells decreases. The turgidity of the petal cells decreases causing the cells to lose rigidity and close. The elastic properties of the cell walls of the plant cells enable the reversible increase and decrease in volume.

The Science: Water is absorbed by the roots of the plant by osmosis. Water moves from the soil, which has a high concentration of water, to the root cells which have a lower concentration of water. The water then travel upwards towards other parts of the plant due to transpiration and capillary action.

Transpiration takes place on the exposed surface of the plant. The concentration of water in the plant cells is higher than the concentration of the water in the air. Hence, water passes from the plant surface to the air due to osmosis. When the amount of water in the plant cells reduces, more water is pulled up to replace it. Hence, osmosis at the roots and the exposed surfaces helps balance the volume of water in the plant.

Water moves in the upward direction due to capillary action. The forces that bind the water molecules together (cohesion and surface tension) and the forces that attract the bound liquid to the plant cells are stronger than the force of gravity. Water which is lost by the cells needs to be replenished as the plant cells need to maintain turgidity to remain rigid.

The presence of water in the vacuole of the plant cell causes the cytoplasm to swell. Hence, the cytoplasm of the cell pushes against the cell wall. The cell wall exerts a pressure on the cytoplasm at the same time. This causes the cell to become turgid. The pressure that the cytoplasm exerts on the cell wall in response is called turgor pressure. When water reduces in the cell, the cytoplasm shrinks away from the cell wall. Turgor pressure is lost and the cell loses its rigidity. This leads to the droopy appearance of stems, leaves and petals.

The Tulip: Temperature dependent petal opening and closing

The opening and closing of the petals is enabled due to change in temperature. Change in temperature activates a protein (phosphorylation) in the cell responsible for opening and closing water channels in plant cells. When the protein is activated, the water channels open up and rapid water transportation takes place to the petals causing them to open up. When the temperature decreases, dephosphorylation results in gating of the water channels. The amount of water reaching the petals reduces, causing them to close eventually. The petals open at a temperature of 5oC and close at a temperature of 20oC.

The abaxial tissue on the lower side of the perianth increases in length at a low temperature, where as the abaxial tissue on the upper side of the perianth increases in length at a high temperature. This causes the petals to bend outwards during high temperatures and inwards during low temperatures.

The flower opens up but still maintains the cup shape. method experiments Method failure | success

The main aim of the study was to explore the biological actions occuring in thermonastic plant. The mechanisms of the organisms in concern were thoroughly observation | interpretation analysed and the effects of temperature and water pressure on the thermonastic flowers, were studied in detail. The study was then centred around the effects of capillary action in various materials. new experiments An attempt was made to understand this mechanism by experimenting with a man- failure | success made material having properties similar to the petals of a flower. Paper was, thus, chosen as the basic material for experiments owing to its fibrous nature which interpretation facilitates capillary action. new experiments The effects of capillary action were further explored by playing around with prototypes of various shapes, geometry and made out of varying thicknesses of paper.

The need for a fibrous material restricted the variation in materials to different textures and densities in paper. Hence, one set of experiment was performed to check the effects of capillary action of water over materials that were non-reactive to water. Composite materials were developed to analyse the effect on the combination of hydroscopic and hydrophobic materials.

Upon a deeper understanding of the mechanism and its effect on paper, an attempt was made to channelise the water in a desired manner through the prototypes. The main aim was to try and achieve a control over the motion exhibited in the prototypes due to capillary action. The observations of various experiments conducted, guides the study to the point of trying to control the occuring motion.

However, no successful attempts were developed in trying to reverse the same mechanism. PRODUCED BY AN AUTODESK EDUCATIONAL PRODUCT

PROTOTYPESeries 1 One Prototypes

Aim: Aim: To test the effect of capillary action on paper using flowers of different shapes and PRODUCED BY AN AUTODESK EDUCATIONAL PRODUCT To testsurface the effect areas. of capillaryThe objects action areon paperexposed using to flowers water of at different different shapes temperatures. and surface areas. The objects are exposed to water at different temperatures. PRODUCED BY AN AUTODESK EDUCATIONAL PRODUCT

Materials:Materials: - Paper ( thin, medium) - Paper ( thin,- Car medium)dboard (thick) - Cardboard- Water (thick) (hot, room temperature, cold) - Water (hot, room temperature, cold) Material properties: Material properties: 1. Different types of flowers are tested based on area of base 7 cm2 2 1. Different- Thicknesstypes of flowers - Thin, are testedmedium based and on thick – flowers area of petal: 5.9 cm - Shape - Thickness- Sha- Thin,pe mediumof Flower and thick flowers

- Shape PRODUCT EDUCATIONAL AUTODESK AN BY PRODUCED - Shape of Flower Surface Area Exposed to Water Perimeter of edges in contact with water Pointed Petal 10.2 sq.cm 7.00 sq.cm Rounded Petal 0.8cm 3.2 cm

PRODUCED BY AN AUTODESK EDUCATIONAL PRODUCT 2. Water at different temperatures was used –

- Hot water - 212o F - 2. WaterNormal temperature at different – 71 otemperatures F was used - Cold water- Hot - 50 owater F - 212o F - Normal temperature – 71o F Procedure: - Cold water - 50o F area of base 10.2 cm2 The paper and cardboard is cut in the shape flowers. The petals are folded inwards towards the centre area of petal: 2.4 cm2 to resemble the flower in its closed state. The flowers are then placed in the bowl of water with its petalsProcedure: facing upwards. The paper and cardboard is cut in the shape flowers. The petals are folded inwards

towards the centre to resemble the flower in its closed state. The flowers are PRODUCT then EDUCATIONAL AUTODESK AN BY PRODUCED placed in the bowl of water with its petals facing upwards. Response:

1. The range of motion and opening time for flower with larger surface area (round- ed petals) :

2. The range of motion and opening time for flower with smaller surface area (pointed petals) : experiment 1 method Experiment one included two different types of flowers, three different temperatures and three papers with different thickness.

Paper is made of fibers of cellulose from wood pulp. When the paper is folded, the 00.00 fibres get squeezed and compacted on the inside of the fold. As water soaks up the 00.40 paper, the squeezed fibres in the paper expand. The swelling fibers push outwards, 00.61 unfolding the paper.

As the density of the fibre increases, the rate of water getting soaked up decreases, thus increasing the time taken for the fibres to expand and swell out. 00.82

The surface area exposed to water also affects the time taken for the paper flower to open up.

Hence, if the surface area in touch with water is more, the rate at which water gets absorbed increases and the flower opens at a faster rate. The water seems to get absorbed and travels through the edges. Range of opening of medium paper flower on room’s temperature water. Series Two Prototypes

Aim: To study range of motion in elastic objects when filled with steam or air

Materials : - Balloon - Water Bottle - Plastic Paper - Straw

Material properties : - Balloon is made of rubber which is elastic by nature. The base of the bottle is cut off in order to use it as a funnel to channelise steam. - Two leaves are cut from the plastic sheet and sealed around the edges as well as at various points at the centre. An opening is left at the base to insert a straw. This allows the air to be channelised into the sealed leaf. Steam from boiling water slowly fills up the ballon. Procedure: - The balloon is inserted on the water bottle. The bottle is placed in a pan of boiling water. Steam is allowed to rise into the balloon. Care is taken to ensure that there is no air in the balloon already. - The same balloon is filled with air as well as water. - A straw is inserted into the sealed leaf. Air is blown into the sealed leaf through the straw.

Response : The balloon inflates at a very slow rate when steam is pumped into it. It expands by only 10% when inflated using steam for 5minutes as compared to 100% when it is inflated by pumping in air for 1 minute. The balloon expands to 100% when filled with water too. Hence, even though steam can be used as a medium to inflate and deflate objects, it works very slowly and is not as effective as air or water.

When air is pumped into the leaf through the straw, it inflates and becomes stiff. It deflates and looses its rigidity when the air is released from the pumped up leaf.

Air inflated into plastic leaf with sealed “nerves” to understand capillary action. Series Three Prototypes

Aim: To study the effects of capillary action on different forms created out of paper with varying thickness.

Materials: - Paper - Cardboard - Water

Material properties: - Paper rolled up in tubes - Paper strip folded in a zig-zag manner - Cardboard spiral

Procedure: The paper rolls are cut in half and folded into a V-shape. Water is dropped over the cut portion. Paper strip folded in a zig zag manner is dropped in water. Cardboard spiral is put into water.

Response: Water seeps in through the cut portion of the paper rolls due to capillary action differents shapes causing the rolls to straighten up.

The folded paper takes in water through the edges in contact with the water surface. The pressure of the water causes the folds to open up and the paper straightens up over the surface of water.

The cardboard spiral pulls the water upwards causing the spiral to be pulled downwards at a rate proportionate to the rate of flow of water. Series Four Prototypes

Aim: To study the effects of capillary action on composite materials

Materials: - Paper of medium thickness 00.05 - Plastic - Paper with metallic finish on one surface - Water

Material properties: - Paper - hydroscopic - Paper with metallic finish on one side- hydrophobic - Plastic - hydrophobic 00.15 Procedure: The paper with medium thickness is cut into the shape of a flower with the upper portion of the petal cut off. Plastic is cut in the shape of the upper triangular portion of the petal and stuck over the paper using a cello-tape. This combination of paper and plastic is then put into water.

A paper flower is cut out of the paper with metallic finish. The paper flower is dipped 00.21 in water with the surface having metallic finish used as the base.

Response: The flower made out of a combination of paper and plastic opened from an angle of ~ 80o to 180o. 00.58 The flower with the metallic finish did not react in any way with the water. The flower made from paper and plastic opened because the material that constituted the base and was in contact with the water was paper (hydroscopic material). The capillary action of water exerted pressure on the lower part of the flower made out of paper causing the flower to open up. No effect was observed on the edge of the 00.81 paper in contact with the plastic. This indicates that the unfolding action of the paper is due to the water contact at the base and not due to water rising till the top of the petal making it heavy. The paper flower with metallic finish was dipped in the water with the metallic surface 01.41 at the base. The flower did not open up indicating that the base did not absorb water or exhibit any capillary action. Series Five Prototypes

Aim: To study the effects of capillary action on paper flower having a steady and constrained base

Materials: - Paper of medium thickness - Copper wire - Water RANGE OF MOTION - Scotch tape

Material properties: - Paper - hydroscopic - Copper wire – non-reactive to water

Procedure: The paper with medium thickness is cut into the shape of a flower. Copper wire is attached at the base of the flower, bending slightly upwards over the petals upto midway along the petal length. This resembles veins of the flower petals. The wire is attached to the petals using a scotch tape. The prototype is then dipped into a bowl of water.

Range of motion: The petals of the flower opened to an angle of ~ 70o from ~ 10o. This change took place over a period of approximately four and a half minutes.

Response: The copper wire attached at the base of the flower acted as stiffeners holding the petals steadily in position. This constrained the range of motion of the petals. The side view | closed top view | closed petals opened upto an angle of 70oas opposed to an angle of 180oin the rest of the cases. The use of stiffeners made out of a material that was non-reactive to water increased the time taken by the petals to open up. place over a period of approximately four and a half minutes. Series Six Prototypes

Aim: To study the effects of capillary action on the paper petals when focusing water contact to a single point.

1origami

Materials: - Medium thickness paper - Straw - Polystyrene

Material Properties:

Origami- The medium thickness paper was folded into the form of a tulip using origami paper folding instructions. The base of the flower (the tip) was inserted in a polystyrene base with a cut-out. This ensured that only the tip of the flower was in contact with the water when placed in it. Polystyrene was used due to its non-reactive nature – as it does not react with the water, the change in the unit is only due to the paper reacting with water. The petals were folded inwards at the top base. Origami 2straw was tried in order to study the effect single point contact, paper folds, increasing paper surfaces and increasing height of folded petal edge has on rate of water movement.

Straw base- Individual petals with long stalks are cut from the medium thickness paper. Petals are joined to form a complete flower by stapling the petal edges to each other. The flower is inserted in the straw and placed in water to ensure single-point contact with the water.

Polystyrene base – Individual petals with long stalks are cut from the medium thickness paper. Petals are joined to form a complete flower by stapling the petal edges to each other. The polystyrene is molded to form a base for the flower. A cut-out is made in the base to insert the flower. The paper flower was glued to the polystyrene base. This method is used to ensure single point contact of paper with the water. The polystyrene flower base provides a floating steady base for the flower. 3polysterine base POLYSTERINE base

Procedure: Each prototype was dipped in water at room temperature.

Response:

Origami- The rate at which the water rose up slowed down considerably. The water reached the folded paper edge after 25 minutes. However, the folded petal did not open up. The reduced rate of rise can be attributed to increase in complexity of the unit as well as the single-point contact. Though the same material was used, folding the paper to form the tulip increased the number of edges as well as surfaces that the water needed to rise up through.

Straw base – The rate at which the water rose up slowed down considerably. The water reached the folded paper edge after 15 minutes. However, the folded petal did not open up.

Polystyrene base – The water did not rise up through the flower. This may be attributed to the fact that the paper was glued to the polystyrene. This may have changed the cellular structure of the paper not allowing the water to rise through it due to capillary action. sketches model Series Seven Prototypes

Aim:

To study the effects of capillary action on paper by channelizing the water in certain directions

Materials: - Paper of medium thickness - Cardboard - Wat

Material properties:

Lamination - The paper flower was made in layers using a paper of medium thickness. lamination Seven flowers of decreasing surface area were glued one on top of the other to create a composite flower. Layering of petals helped to create varying thickness along the petal length. Reducing the flower surface area for each layer helped increase the total perimeter of the edges in contact with water

Chiseling – This flower was cut out of a 4 mm thick cardboard. The petals of the cardboard flower were divided into three parts. Layers were scraped off from the petal parts such that the final petal had a different thickness for each part. The first part from the centre was 4mm thick, the next 3mm and the last part was 2mm thick. This helped create a layered flower using a single material.

Composite - A two-layered flower was made using cardboard and paper. A cardboard flower was made with veins cut in the petals. Paper petals were cut and pasted to the outer surface of the cardboard petals such that the paper did not touch the base of the cardboard flower. This ensured that any water that transferred to the paper petals was from the cardboard and not directly from water. The veins helped increase the length of the edges of the cardboard in contact with the water as well as the paper. composite

Procedure:

Each prototype was dipped in water at room temperature.

Response:

The flowers in each case opened to an angle of 180o.

Lamination – The rate at which the water rises upwards is reduced due to the layers of the flowers. The layers increase the thickness of the base. Even though the length of the edges in contact with the water increases, the rate of water movement is slowed down. This indicates that thickness of paper has more effect on capillary action as opposed to edge length. channeling water The petals open up after 7 seconds. through cutouts range Chiseling – A response similar to the laminated flower is seen in the chiseled flower.

Composite –In the two layered flower, the cardboard vein cut-outs channelize the direction of water rather than letting the water rise in a normal manner. This chiseling experiment helps understand whether guiding the direction of water rise can assist in controlling the motion of the petals.

lamination

composite Speculation

Prototype for a bioclimatic façade

The building envelope is the interface between the internal and external environment of a building. It is important to focus on the envelope design for better building performance - to help decrease resource use, increase occupant comfort and improve aesthetics of the building. Responding to the external temperature is important to improve the thermal performance of the building. High performance elements that are dynamic and respond to changes in the external temperature should be incorporated in façade design. At high temperatures, the elements should enable heat loss and ventilation and at low temperatures, the elements should enable heat gain and insulation. Through this study, we hope to develop concepts for high performance mechanisms that respond to changes in temperature.

The floating city

And why only a facade? Instead of having the mechanism as a repeated part of the cell, the mechanism could become the cell itself. A floating cell that takes advantage of the water and its properties related to heat. The cell would have roots that are sunk into the water and get filled with it. During the day, and as the solar radiation heats up the night water the cell would start to open. Each “leaf” of the cell would have three parts and day at the upper part it would have shading mechanisms. As the day passes the floating city keeps opening up, till it gets dark and cooler again and consequently the cell goes back to close mode again in order to protect its inhabitants. References -F.M.Andrews. (1929). The effect of temperature on Flowers. Indiana: Department of Botany, Indiana University.Tanaka, O., Tanaka, Y., & Wada, H. (1988). -Photonastic and thermonastic Opening of Capitulum in Dandelion, Taraxacum offinale and taraxacum japonicum. The Botanical Magazine, Tokyo.Azad, A. K., Sawa, Y., Ishikawa, T., & Shibata, H. (2004). -Phosphorylation of Plasma membrane Aquaporin Regulates Temperature Dependent Open- ing of Tulip Petals. Plant Cell Physiol.45 (5):608-617 . -http://www.theplantexpert.com/springbulbs/Tulip2DoubleEarly.html -http://www.ipm.iastate.edu/ipm/hortnews/1998/9-4-1998/tulipclasses.html -http://www.floridata.com/ref/t/tulip_spp.cfm -http://www.ivydenegardens.co.uk/Bulb%20Colchicum%20Crocus%20Gallery/colcrocbulbintr. html -http://www.dailypuppy.com/articles/can-you-pollinate-tulips/356bc02f-8060-8bfa-cc03- d7803d0713bd -http://en.wikipedia.org/wiki/Tulip -http://en.wikipedia.org/wiki/Medicago_marina -http://content.yudu.com/Library/A1og25/PlantsADifferentPers/resources/119.htm -http://en.wikipedia.org/wiki/File:Medicago_marina-linedrawing.png -http://www.ivydenegardens.co.uk/Bulb%20Colchicum%20Crocus%20Gallery/colcrocbulbintr. html -Floral Movements in response to Thunderstorms improve reproductive effort in the alpine species Gentiana Algida [Gentianaceae], Michael R. Bynum and William K. Smith -http://www.bmyersphoto.com/BWXRAY/vegetables3.html