Morphology of flowering plants.pptx Biology

Remedial Biology

1. Morphology of Leaf dr.aarif CHARACTERISTIC S O F LEA F : L e a f i s a thin, expanded , green structure. T h e gr e e n co l o u r of t h e l e a f i s due t o t h e pr e s e n ce of c h l or o p h y l l p i gme n t . I t i s exogenou s i n or i g i n . I t i s b o r n e on t h e s t e m a t the nod e . A n axillar y bu d i s of t e n pr e s e n t i n t h e axi l of e a ch l e a f. I t h a s limited growth. I t do e s n ot p o ss e s s a p i c a l b u d or a r e gu l a r gro w i n g p o i n t . A dorsi-ventrally compressed, lateral appendage of stem produced at the node s a n d i s s p e c i a l i zed t o p e rf o rm p h o t o s y n t h e s i s

2. Morphology of Leaf LEA F BAS E O R HYPOPODIUM: T he pa rt of l e a f at t ache d t o t he s t e m or br a nch i s kno w n a s l e a f ba se. I t may as s ume dif f e r e nt shape s i n di ffer e nt p l an t s. I n so m e l e g um i nous p l an t s , t he l e a f b l ade ma y becom e s w o l l e n w hich i s ca l l e d pulvinus . I n monoco t s , t he l e a f ba se e xp and s i n t o a sh e a t h c o v erin g t he s t e m par t ia l l y or completely. Leaves of some plants possess a pair of l a t e ral ou t g ro w t h s at t he ba se , on ei t h e r s i d e s of ax i ll ar y b u d . T h e se ou t g r o w ths are ca l l e d s tip ule s an d s uch l e a v e s ar e ca l l e d stipulate leaves. T he l e a v e s w i t hout s t i p u l e s ar e ca l l e d e x - stipulate leaves. Stipules are usually green . T he ma i n fu nc t i ons of s t i p u l e s ar e t o p r otec t t he bud an d carry out photosynthesis . P A RT S O F A TYP I CA L LEA F : PULVINUS dr.aarif SH E A TH STIPULES

3. Morphology of Leaf P A RT S O F A TYP I CA L LEA F : P E TIO L E O R MESOPODIUM: Pe t i o l e i s t h e p a rt of l e a f con n e c t i n g t h e lami n a w it h t h e b r a n ch or s t e m. L e a v e s t h a t p o ss e s s p e ti o l e are c a ll e d petiolat e a n d l e a v e s w it h o u t petiole are called non-petiolate or sessile leaves. Pe t i o l e i s us u a ll y cylindrica l , b u t may be h o l l ow ( P a p a y a ) , t ub u l a r or flattened. Fun c ti on of p e ti o l e i s t o raise t h e l a m i n a t o ex p o s e i t t o m ore light a n d ai r a n d t o h e l p i n con duc t i o n . dr.aarif

4. Morphology of Leaf P A RT S O F A TYP I CA L LEA F : LAMIN A O R E P I P ODIUM: This is the largest , most important, gree n a n d f l a tt e n e d p a rt of t h e l e a f. It plays a vital role in photosynthesis, gaseous exchange and transpiration. T h e l e a f i s k n o w n a s do r siv e nt r al w h e n it s v e n t r a l surf a ce i s s t ruc t ur a ll y d i ff e r e n t fr o m dors a l su r f a c e , e . g. dicotyledonous leaves. T h e l e a v e s h a v i n g b o t h s i m i l a r su r f a c e s a re ca l l e d isobilatera l . Such l e a v e s a re fo u n d i n m o n oco t p l a n t s dr.aarif

5. Morphology of Leaf LEA F VENATIO N : The arrangement of veins and veinlets in the lamina is known as venation. The veins are in fact conducting strands of lamina. They are concerned with the conduction of water, mineral salts and food and form the structural framework of the lamina. RETICULATE PARALLEL dr.aarif

6. Morphology of Leaf RETICULAT E VENATION : W h e n t he v e i ns an d v e i n l e t s form a networ k , i t i s ca l l e d r e t i cu l a t e venation. Her e t he m i dri b i s cent r all y p l aced an d v e i ns an d v e i n l e t s rem a i n di s t ri b u t e d lat era lly . I t i s found i n dico t yled onous p l an t s. On the basis of number of mid-veins, Unic o st ate - w i t h a s i n g l e mi d - v e in ( e .g. M an g o ) Mu ltico s tat e - w i t h t w o or m ore prom i n e nt v e i ns ( e .g. Zi z yphu s ) . I t may be c o nv e r g e nt or diver g e n t . dr.aarif

7. Morphology of Leaf P A R A L L E L VEN A T ION : I n t h i s t y p e of v e n a ti o n , vein s i n l a m i n a run a l most paralle l t o one another. I t i s f o u n d c o mmo n l y i n monocotyledonous plants. I t i s of t h e fo l l o w i n g t w o t y p e s: Uni c os t ate e . g . , Ba n a n a , Canna. Multicostate e . g . , Gras s , r i c e , bamboo, etc dr.aarif

8. Morphology of Leaf SIMP L E LEA F : S i mp l e l e a v e s a re t h o s e i n w h i ch single l e a f b l a de or lamina i s present, e . g . , M a n g o , P e e p a l , P a p a y a , etc. COMPOUN D LEA F : Compo u n d l e a v e s a re t h o s e i n w h i ch t h e l e a f b l a de or l a m i n a i s d i v i de d i n t o n umb e r of s e gme n t s k n o w n a s leafle ts or pinnae . T h e l e a f l e t s n e v e r b e a r a x i l l a ry b u d s i n t h e i r a x i l . dr.aarif

9. Morphology of Leaf COMPOUN D LEA F : a) Pinnately compound leaves: I n t h i s t y p e t h e l e a f l e t s a re pr e s e n t l a t e r a ll y on a common a x i s c a ll e d rachis , w h i ch r e pr e s e n t s t h e midrib of t h e l e a f ( e .g . Gol d mo h u r , Ca s s i a ) T h e re a re of fo u r k i n d s of p i nn a t e l y comp o u n d l e a v e s as Unipinnate Bipinnate Tripinnate Decompound dr.aarif

10. Morphology of Leaf COMPOUN D LEA F : b) Palmately compound leaves: A l l t h e leaflets of t h e pa l m a t e l y comp o u n d l e a v e s a re a t t a c h e d a t a com m o n point , i . e . a t t h e ti p of p e ti o l e , l i ke f i n g e rs of t h e palm. T h e re a re f i v e t y p e s of p a l ma t e l y comp o u n d l e a v e s a s: Unifoliate Bifoliate Trifoliate Quadrifoliate Multifoliate. dr.aarif

11. Morphology of Leaf PHYLLOTAXY : Phyllotaxy is the arrangement of leaves on the stem and branches ALTERNAT E PHYLLOTAXY : I n t his t y pe, s in g le leaf ar i s es at eac h node. T he l e a v e s ar i se lat era lly on t he s t e m or br a nch e s, e . g . , Sunf l o w e r, M an g o, China ro s e , M us t ar d e t c. dr.aarif OPPOSIT E PHYLLOTAXY: In this type, two leaves arise from each node in opposite direc t i on. I t i s of t w o t ypes: D E CUS S A T E : W h e n on e pai r of l e a f i s p l ace d a t r ig h t angle t o next or lower pair of leaf, it is said to be opposite decussate ph y ll o t ax y . e . g . , Cal o t rop i s , O cim u m , e t c. SUPERPOSED : In this type, all the pairs of leaves on the stem are arranged one above the other, e.g., Jamun, Guava, etc. WHORLE D O R VERTICILLAT E PHYLLOTAX Y : I n t his t y p e more tha n two leav e s ar i se from e a c h n o d e and form a w ho r l aroun d i t . e . g . , N e ri u m , A l s t onia

12. Morphology of Leaf LEAF SPINES: I n s o me xerophyti c p l an t s l i ke O p un t i a , t h e en t i re l ea f g e t s mod i f i e d i n t o a s m a ll , s t i ff, po i n t e d s t ruc t ure c a ll e d spine t o c he ck transpiration. Some t i mes o n l y a p a rt of l ea f such as stipules , get modified into spines , t o pr o t e ct p l an t s fr o m gr a z i n g animals, - e . g . , Z i z y p h us an d Ac a c i a . M O DIFIC A TION S O F L EA VES : dr.aarif

13. Morphology of Leaf LEAF TENDRILS : - I n c e r t a i n p l an t s ha vi n g weak ste m , en t i re leaf or a par t of i t g e t s modified into an elongated , thin, c y l i n dr i c a l , coile d , wiry , s en s i t iv e s t ruc t ure k n o w n a s ten dr i l . T he s e t en dr i l s h e l p th e p l an t to c l i mb up on som e support . I n w i l d pe a ( L a t h y ru s ) , entir e l ea f i s tendrillar, i n s w e e t pe a ( P i su m sa ti vu m) t e rm i na l leaflets a re t e n dr i ll a r , i n Glor i o s a o n l y t h e leaf ap e x mod i f i e s i n t o t en dr i l , an d - i n Sm i lax , stipules b e come t en dr i ll a r. M O DIFIC A TION S O F L EA VES : dr.aarif

14. Morphology of Leaf M O DIFIC A TION S O F L EA VES : LEA F HOOKS: In Bignonia unguis-cati (Cat's nail), the terminal three leaflets get mod i f i e d i n t o t hr e e s t i ff curve d & p o i n t e d hook s w h i ch l o o k l i ke cat's nail . They cling to bark of tree ( support ) a n d h e l p t h e p l a n t for climbing . B i g n o n i a i s a n e l e g a n t h o o k - c l i mb e r dr.aarif

15. Morphology of Leaf PHYLLODE: I n s o me p l an t s , p e t i o l e bec o mes fla t , green and leaf like and performs phot o synthesis. T h i s i s k n o w n a s phyllode . For e x a mp l e , i n Ac a c i a auriculiformis, the normal leaf is b i p i nna t e l y comp o u n d an d falls off soon. T h e p e t i o l e g e t s mod i f i e d i n t o p h y l l od e . T h i s i s x e ro ph y t i c adaptation to reduce transpiration M O DIFIC A TION S O F L EA VES : dr.aarif

16. V en a t i on Reticulate P a r al l el Unicostate Multicostate Unicostate Multicostate T yp e s Simp l e Compound Pinnately Phyllotaxy Opposite Palmately Alternate Decussate Superposed Modifications T e n dr i l Hook P h y llode Whor l ed Spine Whole leaf Terminal leaflet Apex St i p u l es